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Sample records for estuarine crab neohelice

  1. Dietary copper effects in the estuarine crab, Neohelice (Chasmagnathus) granulata, maintained at two different salinities.

    PubMed

    Sabatini, Sebastián E; Chaufan, Gabriela; Juárez, Angela B; Coalova, Isis; Bianchi, Laura; Eppis, María R; Ríos de Molina, María del Carmen

    2009-11-01

    We analyzed the dietary copper effects in the estuarine crab Neohelice (Chasmagnathus) granulata and its interaction with water salinity. Crabs were maintained at 2 per thousand and 30 per thousand salinity for 5 weeks and they were fed with commercial food supplemented with the green alga Scenedesmus vacuolatus previously exposed to copper. No mortalities were observed, but crabs maintained at 2 per thousand salinity accumulated on average 40% more copper compared to animals maintained at 30 per thousand salinity. At 2 per thousand salinity, superoxide dismutase (SOD) activity and reduced glutathione (GSH) levels were increased at the first and second weeks, respectively, while lipid peroxidation and protein oxidation were evident after 4 weeks of copper exposure. At 30 per thousand salinity, all measured variables increased progressively but were significantly higher only at the end of the assay (5th week), except for protein oxidation that remained unchanged throughout the experiment. The hepatosomatic index (HSI) was significantly decreased in response to copper exposure, but only in crabs acclimated to 2 per thousand. These findings have suggested that dietary copper exposure induces greater metal accumulation and larger oxidative stress responses in crabs maintained at 2 per thousand salinity.

  2. Effects of zinc on molting and body weight of the estuarine crab Neohelice granulata (Brachyura: Varunidae).

    PubMed

    Beltrame, María Ornela; De Marco, Silvia G; Marcovecchio, Jorge E

    2010-01-01

    The semiterrestrial burrowing crab Neohelice granulata is one of the main inhabitants of the supratidal and intertidal zones of brackish salt marshes, estuaries and coastal lagoons from South America's Atlantic littoral. A large population of this species spreads out Mar Chiquita coastal lagoon (in Argentina) and its corresponding wetlands, and is considered as a key species within this system. Since high values of dissolved heavy metals (including Zn) have been recently reported within Mar Chiquita coastal lagoon, with levels unusually higher than those from other coastal systems within Argentina, it has been explored that the existence of a risk of environmental conditions endanger these populations. So, juveniles of this estuarine crab were experimentally exposed to increasing concentrations of dissolved Zn (i.e., 0, 0.5 and 1 mg Zn(2+)L(-1)) during six months, the time involved between two successive molts; in addition, both the size and weight reached after each molt were also studied in this assay. It can be concluded that zinc can be toxic to crabs only at high concentrations. Considering that levels up to 1 mg ZnL(-1) were recently reported in Mar Chiquita coastal lagoon waters, the potential occurrence of mean chronic effects on the crab population within the coastal lagoon is discussed.

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

    PubMed

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

    2008-11-01

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

  4. Effects of atrazine on ovarian growth, in the estuarine crab Neohelice granulata.

    PubMed

    Silveyra, G R; Canosa, I S; Rodríguez, E M; Medesani, D A

    2017-02-01

    Atrazine, a herbicide that is intensively used in Argentina, was assayed to evaluate the alteration of reproduction in a wild species of crustaceans. Adult females of the estuarine crab Neohelice granulata were exposed to formulated atrazine during the 3-month pre-reproductive period. Three atrazine concentrations (0.03, 0.3 and 3mg/L) were assayed, together with a water dilution control. At the end of the exposure period, several variables concerning the energetic status of animals were measured, such as weight gain, glycemia, and energy reserves in both muscle and hepatopancreas. The gonadosomatic index (GSI) was also determined, as well as the proportion and relative area of each oocyte type in histological sections. Besides, the total content of vitellogenin proteins (Vg) in both ovary and hepatopancreas was measured. A significant (p<0.05) decrease of glycogen content was observed in muscle, while a significant (p<0.05) lower area of both previtellogenic and vitellogenic oocytes was verified in the ovary by effect of atrazine, in correspondence with a Vg content significantly (p<0.05) diminished in the ovary and augmented in the hepatopancreas. Besides, a higher proportion of previtellogenic oocytes were seen by effect of atrazine. Taken together, these results indicate a clear reduction and delay in the ovarian growth of the studied species, during the period at which the ovary normally grows up prior to spawning. On the other hand, a decrease of Vg content was observed at 0.3 and 3mg/L of atrazine after 24-h in vitro assays carried out with ovarian explants, providing additional evidence about the inhibitory role of this herbicide on the ovarian growth. These results encourage future research on deleterious effects of atrazine on crustacean reproduction.

  5. Effects of glyphosate on egg incubation, larvae hatching, and ovarian rematuration in the estuarine crab Neohelice granulata.

    PubMed

    Avigliano, Luciana; Alvarez, Natalia; Loughlin, Camila Mac; Rodríguez, Enrique Marcelo

    2014-08-01

    Ovigerous females of the estuarine crab (Neohelice granulate) were exposed to both pure glyphosate (2.5 mg/L and 5 mg/L) and a glyphosate formulation (Roundup Ultramax, containing glyphosate at 2.5 mg/L acid equivalent). At the end of the egg incubation period, a significant reduction in the number of hatched larvae was seen as a result of Roundup exposure. Additionally, several larvae abnormalities were seen in both pure glyphosate (2.5 mg/L) and Roundup treatments, such as hydropsy and hypopigmented eyes, and atrophied eyes were observed in the Roundup treatment. To evaluate the effect of the herbicide on ovarian rematuration, females remained exposed for 32 d. Pure glyphosate at 2.5 mg/L stimulated ovarian maturation over control levels, mainly in terms of a higher gonadosomatic index and a higher percentage of vitellogenic oocytes. A plausible hypothesis to be tested in further experiments is that exposure to glyphosate disrupts the hormonal system controlling reproduction.

  6. Copper effects on key metabolic enzymes and mitochondrial membrane potential in gills of the estuarine crab Neohelice granulata at different salinities.

    PubMed

    Lauer, Mariana Machado; de Oliveira, Camila Bento; Yano, Natalia Lie Inocencio; Bianchini, Adalto

    2012-11-01

    The estuarine crab Neohelice granulata was exposed (96 h) to a sublethal copper concentration under two different physiological conditions (hyperosmoregulating crabs: 2 ppt salinity, 1 mg Cu/L; isosmotic crabs: 30 ppt salinity, 5 mg Cu/L). After exposure, gills (anterior and posterior) were dissected and activities of enzymes involved in glycolysis (hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase), Krebs cycle (citrate synthase), and mitochondrial electron transport chain (cytochrome c oxidase) were analyzed. Membrane potential of mitochondria isolated from anterior and posterior gill cells was also evaluated. In anterior gills of crabs acclimated to 2 ppt salinity, copper exposure inhibited hexokinase, phosphofructokinase, pyruvate kinase, and citrate synthase activity, increased lactate dehydrogenase activity, and reduced the mitochondrial membrane potential. In posterior gills, copper inhibited hexokinase and pyruvate kinase activity, and increased citrate synthase activity. In anterior gills of crabs acclimated to 30 ppt salinity, copper exposure inhibited phosphofructokinase and citrate synthase activity, and increased hexokinase activity. In posterior gills, copper inhibited phosphofructokinase and pyruvate kinase activity, and increased hexokinase and lactate dehydrogenase activity. Copper did not affect cytochrome c oxidase activity in either anterior or posterior gills of crabs acclimated to 2 and 30 ppt salinity. These findings indicate that exposure to a sublethal copper concentration affects the activity of enzymes involved in glycolysis and Krebs cycle, especially in anterior (respiratory) gills of hyperosmoregulating crabs. Changes observed indicate a switch from aerobic to anaerobic metabolism, characterizing a situation of functional hypoxia. In this case, reduced mitochondrial membrane potential would suggest a decrease in ATP production. Although gills of isosmotic crabs were also affected by copper exposure, changes

  7. Effect of melatonin in the antioxidant defense system in the locomotor muscles of the estuarine crab Neohelice granulata (Decapoda, Brachyura).

    PubMed

    Geihs, Márcio Alberto; Vargas, Marcelo Alves; Maciel, Fábio Everton; Caldas, Sergiane Souza; Cruz, Bruno Pinto; Primel, Ednei Gilberto; Monserrat, José Maria; Nery, Luiz Eduardo Maia

    2010-03-01

    In vertebrates, many studies verified different effects of melatonin in the antioxidant defense system (ADS). In crustaceans, few studies have been conducted to verify this possibility. We verified the melatonin effects in the crab Neohelice granulata using low (0.002 and 0.02 pmol/crab) and high (2.0 and 20.0 pmol/crab) melatonin dosages in short-term (0.5h) and long-term (9.5h) experiments. We analyzed the antioxidant capacity against peroxyl radicals (ACAP), reactive oxygen species (ROS) concentration, levels of by products of lipid peroxidation (LPO), oxygen consumption (VO(2)), the activity of glutamate cysteine ligase (gamma-GCL) and catalase (CAT) and glutathione content (GSH). Finally, the effects of exogenous melatonin were verified in terms of melatonin and N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK) content in the muscles of N. granulata. In short-term experiment and low dosages, melatonin increased the VO(2), gamma-GCL activity and GSH content (p<0.05) and decreased melatonin content (p<0.05) without effects in ROS, ACAP and LPO (p>0.05). Possibly, melatonin is acting in the ADS increasing its efficiency and/or acting in mitochondrial activity and/or through signaling muscles to increase its consumption. AFMK was only detected in the eyestalk and cerebroid ganglia. In high dosages melatonin effects decreased, possibly by the desensitization of their receptors. In long-term experiment, melatonin decreased ACAP (p<0.05), and CAT activity (p<0.05) in low dosages. In high dosages melatonin reduced VO(2) (p<0.05) and increased ACAP (p<0.05), possibly stimulating others components of the ADS. In conclusion, melatonin in the locomotor muscles of N. granulata affects the antioxidant/pro-oxidant balance in a time and dosage dependent manner.

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

    ERIC Educational Resources Information Center

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

    2016-01-01

    The aim of the present study was to analyze the surface expression of the NMDA-like receptors during the consolidation of contextual learning in the crab "Neohelice granulata". Memory storage is based on alterations in the strength of synaptic connections between neurons. The glutamatergic synapses undergo various forms of…

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Regionalization in the eye of the grapsid crab Neohelice granulata (=Chasmagnathus granulatus): variation of resolution and facet diameters.

    PubMed

    Astrada, Martín Berón de; Bengochea, Mercedes; Medan, Violeta; Tomsic, Daniel

    2012-03-01

    Crabs have panoramic compound eyes, which can show marked regional specializations of visual acuity. These specializations are thought to be related to the particular features of the animal's ecological environment. Modern knowledge on the neuroanatomy and neurophysiology of the crabs' visual system mainly derives from studies performed in the grapsid crab Neohelice granulata (=Chasmagnathus granulatus). However, the organization of the visual sampling elements across the eye surface of this animal had not yet been addressed. We analyzed the sampling resolution across the eye of Neohelice by measuring the pseudopupil displacement with a goniometer. In addition, we measured the facet sizes in the different regions of the eye. We found that Neohelice possesses an acute band of high vertical resolution around the eye equator and an increase in horizontal sampling resolution and lenses diameter towards the lateral side of the eye. Therefore, the analysis of the optical apparatus indicates that this crab possesses greater visual acuity around the equator and at the lateral side of the eye. These specializations are compared with those found in different species of crabs and are discussed in connection to the particular ecological features of Neohelice's habitat.

  11. Neural correlates of expression-independent memories in the crab Neohelice.

    PubMed

    Maza, F J; Locatelli, F F; Delorenzi, A

    2016-05-01

    The neural correlates of memory have been usually examined considering that memory retrieval and memory expression are interchangeable concepts. However, our studies in the crab Neohelice (Chasmagnathus) granulata and in other memory models have shown that memory expression is not necessary for memory to be re-activated and become labile. In order to examine putative neural correlates of memory in the crab Neohelice, we contrast changes induced by training in both animal's behavior and neuronal responses in the medulla terminalis using in vivo Ca(2+) imaging. Disruption of long-term memory by the amnesic agents MK-801 or scopolamine (5μg/g) blocks the learning-induced changes in the Ca(2+) responses in the medulla terminalis. Conversely, treatments that lead to an unexpressed but persistent memory (weak training protocol or scopolamine 0.1μg/g) do not block these learning-induced neural changes. The present results reveal a set of changes in the neural activity induced by training that correlates with memory persistence but not with the probability of this memory to be expressed in the long-term. In addition, the study constitutes the first in vivo evidence in favor of a role of the medulla terminalis in learning and memory in crustaceans, and provides a physiological evidence indicating that memory persistence and the probability of memory to be expressed might involve separate components of memory traces.

  12. Glyceroneogenesis in the hepatopancreas of the crab Neohelice granulata: Diet, starvation and season effects.

    PubMed

    Sarapio, E; Santos, J T; Model, J F A; De Fraga, L S; Vinagre, A S; Martins, T L; Da Silva, R S M; Trapp, M

    2017-02-22

    We determined the activity of glyceroneogenesis from [2-(14)C]-pyruvate, the phosphoenolpyruvate carboxykinase activity, [2-(14)C]-pyruvate oxidation and total lipid levels in the hepatopancreas of the crab Neohelice granulata fed with a carbohydrate-rich (HC) diet or a high-protein (HP) diet and then subjected to 5weeks of starvation, in summer and winter, to determine whether the seasonal adjustments of lipid metabolism to food scarcity are modulated by the composition of the diet previously given to the crabs. The results demonstrated that glyceroneogenesis is an active pathway in N. granulata hepatopancreas, and is regulated by seasonal variations, diet composition and starvation. This study showed that in summer the increase in the hepatopancreas glyceroneogenesis activity is among the strategies used by N. granulata fed an HP diet, to maintain the triglyceride/fatty acid cycle during starvation, a normal condition in the biological cycle of this crab. However, the administration of an HC diet reduced the glyceroneogenesis capacity in response to starvation in summer. In winter, the decrease in the glyceroneogenesis capacity in both fed (HP and HC diets) and starved crabs seems to be a strategy to reduce energy consumption and/or requirement. In contrast to the summer results, the incorporation of [2-(14)C]-pyruvate into (14)CO2 was markedly higher in both diet (HC and HP) groups and in starved crabs during the winter. Four decades after the first study describing the glyceroneogenesis pathway in rat white adipose tissue, this pathway is evidenced for the first time in a crustacean.

  13. Habitat shifts and spatial distribution of the intertidal crab Neohelice ( Chasmagnathus ) granulata Dana

    NASA Astrophysics Data System (ADS)

    Casariego, Agustina Mendez; Alberti, Juan; Luppi, Tomás; Daleo, Pedro; Iribarne, Oscar

    2011-08-01

    Intertidal zones of estuaries and embayments of the SW Atlantic are dominated by the semiterrestrial burrowing grapsid crab, Neohelice ( Chasmagnathus) granulata, and characterized by extensive mud flats surrounded by salt marshes. In this work we examined spatial patterns of distribution of N. granulata during two years to explain their movement patterns. The results of the population sampling showed segregation by sex and size throughout the intertidal, with seasonal variations in densities and different condition indices for adults and juveniles at the different zones. The comparison of seasonal activity (ambulatory activity outside burrows) between marshes and mudflats shows that short term (e.g. daily) variations in activity were controlled by tides. Crabs were active at high tides but increased their activity on days with higher tidal amplitude. Seasonal activity showed that at both areas, females remain with low activity except for a peak in winter, while males showed the highest activity during summer in the mudflat zone, but not so in the marsh. This pattern can be the response to differences in stress tolerance, suggesting that high temperatures are limiting the performance of adult crabs during summer, especially at the marsh where physical conditions can be more critical. The spatial size segregation can be explained by differential mortality in each zone (estimated with tethered crabs), and by the juvenile movement between these zones (estimated with movement traps). Juvenile mortality is higher at the mudflat, while adult mortality is higher in the marsh. Smaller juveniles moved to the marsh, where the mortality is lower, and the larger juveniles moved towards the mudflat. This mortality is due almost exclusively to cannibalism, so our results suggest that this movement of different size classes between zones is controlled, at least in part, by intraspecific predation.

  14. The Southwest Atlantic intertidal burrowing crab Neohelice granulata modifies nutrient loads of phreatic waters entering coastal area

    NASA Astrophysics Data System (ADS)

    Fanjul, Eugenia; Grela, María A.; Canepuccia, Alejandro; Iribarne, Oscar

    2008-08-01

    Along the coastal areas of the Southwest Atlantic estuaries and embayments, phreatic water often circulates through very extended areas (up to several hundred meters perpendicular to the coast), dominated by dense assemblages of deep burrows of the crab Neohelice granulata (formerly Chasmagnathus granulatus). This crab inhabits the intertidal area, from mudflats to marshes vegetated by species of Spartina, Sarcocornia and Juncus, generating extensive burrowing beds where burrow density may reach up to 60 burrows m -2. Since the lower limit of the crab burrows is usually the water table, we investigated through field experiments the effect of N. granulata and their burrows on the chemical characteristics of this phreatic water. Water analysis from experimental (1) occupied burrows (with crabs), (2) unoccupied burrows (where crabs were excluded), and (3) sediment pore water show remarkable differences. Water oxygenation, and nitrate, ammonium and sulphate concentrations inside occupied burrows were higher than in the water inside unoccupied burrows or pore waters. Moreover, directed sampling of phreatic water entering and leaving the crab bed, shows that dissolved inorganic nitrogen concentration is enhanced as the water crosses the crab bed. These results may be ascribed to the fact that in the salt marsh the crabs spend most of their time within burrows, where presumably they store food (plants) and defecate. These activities generate an area of accumulation of excrements and nutrients in different decomposition states. The present work shows a novel way by which bioturbating organisms can affect nutrients exportation from salt marshes to the open waters.

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

    PubMed

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

    2016-08-01

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

  16. Melatonin as a signaling molecule for metabolism regulation in response to hypoxia in the crab Neohelice granulata.

    PubMed

    Maciel, Fábio Everton; Geihs, Márcio Alberto; Cruz, Bruno Pinto; Vargas, Marcelo Alves; Allodi, Silvana; Marins, Luis Fernando; Nery, Luiz Eduardo Maia

    2014-12-04

    Melatonin has been identified in a variety of crustacean species, but its function is not as well understood as in vertebrates. The present study investigates whether melatonin has an effect on crustacean hyperglycemic hormone (CHH) gene expression, oxygen consumption (VO2) and circulating glucose and lactate levels, in response to different dissolved-oxygen concentrations, in the crab Neohelice granulata, as well as whether these possible effects are eyestalk- or receptor-dependent. Melatonin decreased CHH expression in crabs exposed for 45 min to 6 (2, 200 or 20,000 pmol·crab-1) or 2 mgO2·L-1 (200 pmol·crab-1). Since luzindole (200 nmol·crab-1) did not significantly (p > 0.05) alter the melatonin effect, its action does not seem to be mediated by vertebrate-typical MT1 and MT2 receptors. Melatonin (200 pmol·crab-1) increased the levels of glucose and lactate in crabs exposed to 6 mgO2·L-1, and luzindole (200 nmol·crab-1) decreased this effect, indicating that melatonin receptors are involved in hyperglycemia and lactemia. Melatonin showed no effect on VO2. Interestingly, in vitro incubation of eyestalk ganglia for 45 min at 0.7 mgO2·L-1 significantly (p < 0.05) increased melatonin production in this organ. In addition, injections of melatonin significantly increased the levels of circulating melatonin in crabs exposed for 45 min to 6 (200 or 20,000 pmol·crab-1), 2 (200 and 20,000 pmol·crab-1) and 0.7 (200 or 20,000 pmol·crab-1) mgO2·L-1. Therefore, melatonin seems to have an effect on the metabolism of N. granulata. This molecule inhibited the gene expression of CHH and caused an eyestalk- and receptor-dependent hyperglycemia, which suggests that melatonin may have a signaling role in metabolic regulation in this crab.

  17. Damage caused during hypoxia and reoxygenation in the locomotor muscle of the crab Neohelice granulata (Decapoda: Varunidae).

    PubMed

    Geihs, Márcio Alberto; Vargas, Marcelo Alves; Nery, Luiz Eduardo Maia

    2014-06-01

    The aim of this work was to determine whether different durations of severe hypoxia (0.5 mg O2 L(-1)) followed by reoxygenation cause damage to the locomotor muscle of the crab Neohelice granulata. We evaluated reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial membrane potential, and aerobic fiber area of the locomotor muscle after different periods of hypoxia (1, 4, or 10h) followed by 30 or 120 min of reoxygenation. Additionally, changes in cell volume, mitochondrial dysfunction, and infiltration of hemocytes were evaluated after hypoxia and a subsequent 2, 24, or 48 h of reoxygenation. After hypoxia, neither ROS nor LPO increased. However, mitochondrial membrane potential and aerobic fiber area decreased in a time-dependent manner. After reoxygenation, the ROS and LPO levels increased and mitochondrial membrane potential decreased, but these quickly recovered in crabs exposed to 4h of hypoxia. On the other hand, alterations of mitochondria resulted in morphological changes in aerobic fibers, which required more time to recover during reoxygenation after 10h of hypoxia. The locomotor muscles of the crab N. granulata suffer damage after hypoxia and reoxygenation. The intensity of this damage is dependent on the duration of hypoxia. In all experimental situations analyzed, the locomotor muscle of this crab was capable of recovery.

  18. Neural organization of the second optic neuropil, the medulla, in the highly visual semiterrestrial crab Neohelice granulata.

    PubMed

    Sztarker, Julieta; Tomsic, Daniel

    2014-10-01

    Crustaceans are widely distributed and inhabit very different niches. Many of them are highly visual animals. Nevertheless, the neural composition of crustacean optic neuropils deeper than the lamina is mostly unknown. In particular, semiterrestrial crabs possess a highly developed visual system and display conspicuous visually guided behaviors. A previous study shows that the first optic neuropil, the lamina of the crab Neohelice granulata, possesses a surprisingly high number of elements in each cartridge. Here, we present a comprehensive description of individual elements composing the medulla of that same species. Using Golgi impregnation, we characterized a wide variety of cells. Only considering the class of transmedullary neurons, we describe over 50 different morphologies including small- and large-field units. Among others, we describe a type of centrifugal neuron hitherto not identified in other crustaceans or insects that probably feeds back information to every cartridge in the medulla. The possible functional role of such centrifugal elements is discussed in connection with the physiological and behavioral information on visual processing available for this crab. Taken together, the results reveal a very dense and complex neuropil in which several channels of information processing would be acting in parallel. We further examine our results considering the similarities and differences found between the layered organization and components of this crustacean medulla and the medullae of insects.

  19. Serotonin effects in the crab Neohelice granulata: Possible involvement of two types of receptors in peripheral tissues.

    PubMed

    Inohara, Elen Thegla Sander; Pinto, Charles Budazewsky; Model, Jorge Felipe Argenta; Trapp, Márcia; Kucharski, Luiz Carlos; Da Silva, Roselis Silveira Martins; Vinagre, Anapaula Sommer

    2015-07-01

    In crustaceans, serotonin (5-HT) controls various physiological processes, such as hormonal secretion, color changes, reproduction, and metabolism. Since 5-HT injections cause hyperglycemia, this study was designed to further investigate this action of 5-HT in the crab Neohelice granulate, fed with a high-carbohydrate (HC) or a high-protein (HP) diet. The effects of pre-treatment with mammalian 5-HT receptor antagonists, cyproheptadine and methiothepin, were also investigated. A series of in vivo experiments with (3)H-5-HT was carried out in order to investigate the presence of putative receptors in peripheral tissues. Since gills were the tissue with the highest labeling in in vivo experiments, in vitro studies with isolated anterior and posterior gills were also conducted. Cyproheptadine blocked the hyperglycemic effect of 5-HT in HP-fed crabs. Methiothepin reduced glycogen levels in the anterior gills of HP crabs and partially blocked the 5-HT-like posture. The injection of (3)H-5-HT identified specific binding sites in all the tissues studied and revealed that the binding can be influenced by the type of diet administered to the crabs. Incubation of the anterior and posterior gills with (3)H-5-HT and 5-HT confirmed the specificity of the binding sites. Both antagonists inhibited (3)H-5-HT binding. In conclusion, this study highlights the importance of serotonin in the control of glucose homeostasis in crustaceans and provides evidences of at least two types of 5-HT binding sites in peripheral tissues. Further studies are necessary to identify the structure of these receptors and their signaling pathways.

  20. Oxidative effects and toxin bioaccumulation after dietary microcystin intoxication in the hepatopancreas of the crab Neohelice (Chasmagnathus) granulata.

    PubMed

    Sabatini, Sebastián E; Brena, Beatríz M; Pirez, Macarena; de Molina, María Del Carmen Ríos; Luquet, Carlos M

    2015-10-01

    We studied the accumulation and depuration of microcystin-LR (MCLR) in the hepatopancreas of the crab Neohelice granulata fed twice weekly with either non toxic or MCLR-producing Microcystis aeruginosa (strain NPDC1 or NPJB, respectively) during seven weeks. We also analyzed MCLR effects on the oxidative stress- and detoxification-related variables, superoxide dismutase and glutathione-S-transferase activities, and the levels of reduced glutathione and lipid peroxidation (as thiobarbituric acid reactive substances, TBARS). Hepatopancreas MCLR content slightly increased during the first three weeks, up to 8.81±1.84ngg(-1) wet tissue mass (WTM) and then started to decrease to a minimum of 1.57±0.74ngg(-1) WTM at the seventh week (p<0.05 with respect to that in the first week). TBARS levels were about 55% higher in treated than in control N. granulata (p<0.001 and p<0.05) during the first three weeks of the experimental period. GSH content became 50% lower than in control individuals (p<0.01) during weeks 6 and 7. SOD activity was increased by about 2-fold (p<0.05 or p<0.001) from week 3 to 7 in treated crabs with respect to control ones, while GST activity was about 70% higher in treated than in control crabs from week 4 to week 7 (p<0.05). Our data suggest that in the hepatopancreas of N. granulata MCLR accumulation and oxidative damage are limited and reversed by detoxification-excretion and antioxidant mechanisms. The activation of these defensive mechanisms becomes evident at 3-4 weeks after the start of the intoxication.

  1. Metals from mine waste as potential cause of oxidative stress in burrowing crab Neohelice granulata from San Antonio bay.

    PubMed

    Giarratano, Erica; Gil, Mónica N; Marinho, Carmen H; Malanga, Gabriela

    2016-10-01

    The Natural Protected Area San Antonio bay is of particular importance for its congregation of migratory shorebirds and it has been declared one of the Western Hemisphere Shorebird Reserve Network International site (WHSRN). Present study represents the first assessment of variation on oxidative stress biomarkers in male crab Neohelice granulata from San Antonio bay (Río Negro, Argentina) under field conditions, associated mainly to metal contamination coming from passive mining wastes. Three sites were sampled once every three months from November 2012 to August 2013 within this sea inlet (Pile, Fishery and Port) and a control site at the southeast of the bay (Punta Perdices). Accumulation of Ni, Zn, Cr and Al varied only with seasons although without a constant trend, meanwhile Cd, Cu and Pb also varied among sites being highest in Pile and Port. Biochemical results indicated that variations in catalase activity was only site specific being maximum in Pile; meanwhile lipid radical, α-tocopherol and metallothioneins were only seasonal specific being higher in autumn and winter. Seasonal variation was also found for total thioles, being the content higher in summer and autumn than in winter. Correlation analysis revealed that malondialdehyde and α-tocopherol have a positive association with Al and negative with Ni, meanwhile GST has a positive association with Fe. Crabs from the closest area to the waste pile did not exhibit a differentiated oxidative pressure despite the higher accumulation of metals. It is possible that crabs from contaminated areas have developed a tolerance to metals, indicating a strong ecotoxicological selective pressure. More studies are needed to assess whether there is a transfer of metals through the food chain.

  2. Melatonin as a Signaling Molecule for Metabolism Regulation in Response to Hypoxia in the Crab Neohelice granulata

    PubMed Central

    Maciel, Fábio Everton; Geihs, Márcio Alberto; Cruz, Bruno Pinto; Vargas, Marcelo Alves; Allodi, Silvana; Marins, Luis Fernando; Nery, Luiz Eduardo Maia

    2014-01-01

    Melatonin has been identified in a variety of crustacean species, but its function is not as well understood as in vertebrates. The present study investigates whether melatonin has an effect on crustacean hyperglycemic hormone (CHH) gene expression, oxygen consumption (VO2) and circulating glucose and lactate levels, in response to different dissolved-oxygen concentrations, in the crab Neohelice granulata, as well as whether these possible effects are eyestalk- or receptor-dependent. Melatonin decreased CHH expression in crabs exposed for 45 min to 6 (2, 200 or 20,000 pmol·crab−1) or 2 mgO2·L−1 (200 pmol·crab−1). Since luzindole (200 nmol·crab−1) did not significantly (p > 0.05) alter the melatonin effect, its action does not seem to be mediated by vertebrate-typical MT1 and MT2 receptors. Melatonin (200 pmol·crab−1) increased the levels of glucose and lactate in crabs exposed to 6 mgO2·L−1, and luzindole (200 nmol·crab−1) decreased this effect, indicating that melatonin receptors are involved in hyperglycemia and lactemia. Melatonin showed no effect on VO2. Interestingly, in vitro incubation of eyestalk ganglia for 45 min at 0.7 mgO2·L−1 significantly (p < 0.05) increased melatonin production in this organ. In addition, injections of melatonin significantly increased the levels of circulating melatonin in crabs exposed for 45 min to 6 (200 or 20,000 pmol·crab−1), 2 (200 and 20,000 pmol·crab−1) and 0.7 (200 or 20,000 pmol·crab−1) mgO2·L−1. Therefore, melatonin seems to have an effect on the metabolism of N. granulata. This molecule inhibited the gene expression of CHH and caused an eyestalk- and receptor-dependent hyperglycemia, which suggests that melatonin may have a signaling role in metabolic regulation in this crab. PMID:25486055

  3. Object approach computation by a giant neuron and its relationship with the speed of escape in the crab Neohelice.

    PubMed

    Oliva, Damián; Tomsic, Daniel

    2016-11-01

    Upon detection of an approaching object, the crab Neohelice granulata continuously regulates the direction and speed of escape according to ongoing visual information. These visuomotor transformations are thought to be largely accounted for by a small number of motion-sensitive giant neurons projecting from the lobula (third optic neuropil) towards the supraesophageal ganglion. One of these elements, the monostratified lobula giant neuron of type 2 (MLG2), proved to be highly sensitive to looming stimuli (a 2D representation of an object approach). By performing in vivo intracellular recordings, we assessed the response of the MLG2 neuron to a variety of looming stimuli representing objects of different sizes and velocities of approach. This allowed us to: (1) identify some of the physiological mechanisms involved in the regulation of the MLG2 activity and test a simplified biophysical model of its response to looming stimuli; (2) identify the stimulus optical parameters encoded by the MLG2 and formulate a phenomenological model able to predict the temporal course of the neural firing responses to all looming stimuli; and (3) incorporate the MLG2-encoded information of the stimulus (in terms of firing rate) into a mathematical model able to fit the speed of the escape run of the animal. The agreement between the model predictions and the actual escape speed measured on a treadmill for all tested stimuli strengthens our interpretation of the computations performed by the MLG2 and of the involvement of this neuron in the regulation of the animal's speed of run while escaping from objects approaching with constant speed.

  4. Escape response of the crab Neohelice to computer generated looming and translational visual danger stimuli.

    PubMed

    Scarano, Florencia; Tomsic, Daniel

    2014-01-01

    Historically, arthropod behavior has been considered to be a collection of simple, automaton-like routines commanded by domain-specific brain modules working independently. Nowadays, it is evident that the extensive behavioral repertoire of these animals and its flexibility necessarily imply far more complex abilities than originally assumed. For example, even what was thought to be a straightforward behavior of crabs, the escape response to visual danger stimuli, proved to involve a number of sequential stages, each of which implying decisions made on the bases of stimulus and contextual information. Inspired in previous observations on how the stimulus trajectory can affect the escape response of crabs in the field, we investigated the escape response to images of objects approaching directly toward the crab (looming stimuli: LS) or moving parallel to it (translational stimuli: TS) in the laboratory. Computer simulations of moving objects were effective to elicit escapes. LS evoked escapes with higher probability and intensity (speed and distance of escape) than TS, but responses started later. In addition to the escape run, TS also evoked a defensive response of the animal with its claws. Repeated presentations of TS or LS were both capable of inducing habituation. Results are discussed in connection with the possibilities offered by crabs to investigate the neural bases of behaviors occurring in the natural environment.

  5. Regulation of ion transport by pH and [HCO3-] in isolated gills of the crab Neohelice (Chasmagnathus) granulata.

    PubMed

    Tresguerres, Martin; Parks, Scott K; Sabatini, Sebastian E; Goss, Greg G; Luquet, Carlos M

    2008-03-01

    Posterior isolated gills of Neohelice (Chasmagnathus) granulatus were symmetrically perfused with hemolymph-like saline of varying [HCO3-] and pH. Elevating [HCO3-] in the saline from 2.5 to 12.5 mmol/l (pH 7.75 in both cases) induced a significant increase in the transepithelial potential difference (Vte), a measure of ion transport. The elevation in [HCO3-] also induced a switch from acid secretion (-43.7 +/- 22.5 microequiv.kg(-1).h(-1)) in controls to base secretion (84.7 +/- 14.4 microequiv.kg(-1).h(-1)). The HCO3(-)-induced Vte increase was inhibited by basolateral acetazolamide (200 micromol/l), amiloride (1 mmol/l), and ouabain (5 mmol/l) but not by bafilomycin (100 nmol/l). The Vte response to HCO3(-) did not take place in Cl(-)-free conditions; however, it was unaffected by apical SITS (2 mmol/l) or DIDS (1 mmol/l). A decrease in pH from 7.75 to 7.45 pH units in the perfusate also induced a significant increase in Vte, which was matched by a net increase in acid secretion of 67.8 +/- 18.4 microequiv kg(-1) h(-1). This stimulation was sensitive to basolateral acetazolamide, bafilomycin, DIDS, and Na+-free conditions, but it still took place in Cl(-)-free saline. Therefore, the cellular response to low pH is different from the HCO3(-)-stimulated response. We also report V-H+-ATPase- and Na+-K+-ATPase-like immunoreactivity in gill sections for the first time in this crab. Our results suggest that carbonic anhydrase (CA), basolateral Na+/H+ exchangers and Na+-K+-ATPase and apical anion exchangers participate in the HCO3(-)-stimulated response, while CA, apical V-H+-ATPase and basolateral HCO3(-)-dependent cotransporters mediate the response to low pH.

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

    PubMed

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

    2015-11-01

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

  7. Influence of the dark/light rhythm on the effects of UV radiation in the eyestalk of the crab Neohelice granulata.

    PubMed

    Vargas, Marcelo Alves; Geish, Marcio Alberto; Maciel, Fabio Everton; Cruz, Bruno Pinto; Filgueira, Daza de Moraes Vaz Batista; Ferreira, Gabrielle de Jesus; Nery, Luiz Eduardo Maia; Allodi, Silvana

    2010-04-01

    Crustaceans are interesting models to study the effects of ultraviolet (UV) radiation, and many species may be used as biomarkers for aquatic contamination of UV radiation reaching the surface of the Earth. Here, we investigated cell damage in the visual system of crabs Neohelice granulata that were acclimated to either 12L:12D, constant light, or constant dark, and were exposed to UVA or UVB at 12:00h (noon). The production of reactive oxygen species (ROS), antioxidant capacity against peroxyl radicals (ACAP), lipid peroxidation (LPO) damage, catalase activity, and pigment dispersion in the eye were evaluated. No significant differences from the three groups of controls (animals acclimated to 12L:12D, or in constant light, or not exposed to UV radiation) were observed in animals acclimated to 12L:12D, however, crabs acclimated to constant light and exposed to UV radiation for 30min showed a significant increase in ROS concentration, catalase activity, and LPO damage, but a decrease in ACAP compared with the controls. Crabs acclimated to constant darkness and exposed to UV for 30min showed a significantly increased ROS concentration and LPO damage, but the ACAP and catalase activity did not differ from the controls (animals kept in the dark while the experimental group was being exposed to UV radiation). Pigment dispersion in the pigment cells of eyes of animals acclimated to constant light was also observed. The results indicate that UVA and UVB alter specific oxidative parameters; however, the cell damage is more evident in animals deviated from the normal dark/light rhythm.

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

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

    2012-01-01

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

  11. Histopathological changes in gills of the estuarine crab Chasmagnathus granulata (Crustacea-Decapoda) following acute exposure to ammonia.

    PubMed

    de Freitas Rebelo, M; Rodriguez, E M; Santos, E A; Ansaldo, M

    2000-02-01

    Histopathological effects of ammonia on the gills of the estuarine crab Chasmagnathus granulata (Dana, 1851) were evaluated after acute exposure to ammonia concentrations around LC(50) value (17.85 Mm). Disruption of pilaster cells and a subsequent collapse of gill lamellae were the main effects observed. Epithelial necrosis and hyperplasia were also detected. Significant (P<0.05) increases in pCO(2) and lactate, and significant decreases of pO(2) were detected in the haemolymph of ammonia-exposed crabs. These changes suggest that the observed histopathological damage affected gas exchange, possibly leading to death.

  12. Potential effects of physiological plastic responses to salinity on population networks of the estuarine crab Chasmagnathus granulata

    NASA Astrophysics Data System (ADS)

    Giménez, Luis

    2002-12-01

    Chasmagnathus granulata is a South American crab occurring in estuarine salt marshes of the Brazilian, Uruguayan and Argentine coasts. Life history is characterized by an export strategy of its larval stages. I reviewed information on experimental manipulation of salinity during embryonic and larval development (pre- and posthatching salinities), and on habitat characteristics of C. granulata in order to determine potential effects of larval response to salinity in the field and to suggest consequences for the population structure. Local populations are spread over coastal areas with different physical characteristics. Benthic phases occupy estuaries characterized by different patterns of salinity variation, and release larvae to coastal waters characterized by strong salinity gradients. The zoea 1 of C. granulata showed a strong acclimatory response to low salinity. This response operated only during the first weeks of development (during zoeae 1 and 2) since subsequent larval survival at low posthatching salinities was consistently low. Larvae developing at low salinity frequently followed a developmental pathway with five instead of four zoeal stages. The ability to acclimate and the variability in larval development (i.e. the existence of alternative developmental pathways) could be interpreted as a strategy to buffer environmental variability at spatial scales of local or population networks. Early survivorship and production of larvae may be relatively high across a rather wide range of variability in salinity (5-32‰). Plastic responses to low salinity would therefore contribute to maintain a certain degree of population connectivity and persistence regardless of habitat heterogeneity.

  13. Potential effects of physiological plastic responses to salinity on population networks of the estuarine crab Chasmagnathus granulata

    NASA Astrophysics Data System (ADS)

    Giménez, Luis

    2003-01-01

    Chasmagnathus granulata is a South American crab occurring in estuarine salt marshes of the Brazilian, Uruguayan and Argentine coasts. Life history is characterized by an export strategy of its larval stages. I reviewed information on experimental manipulation of salinity during embryonic and larval development (pre- and posthatching salinities), and on habitat characteristics of C. granulata in order to determine potential effects of larval response to salinity in the field and to suggest consequences for the population structure. Local populations are spread over coastal areas with different physical characteristics. Benthic phases occupy estuaries characterized by different patterns of salinity variation, and release larvae to coastal waters characterized by strong salinity gradients. The zoea 1 of C. granulata showed a strong acclimatory response to low salinity. This response operated only during the first weeks of development (during zoeae 1 and 2) since subsequent larval survival at low posthatching salinities was consistently low. Larvae developing at low salinity frequently followed a developmental pathway with five instead of four zoeal stages. The ability to acclimate and the variability in larval development (i.e. the existence of alternative developmental pathways) could be interpreted as a strategy to buffer environmental variability at spatial scales of local or population networks. Early survivorship and production of larvae may be relatively high across a rather wide range of variability in salinity (5-32‰). Plastic responses to low salinity would therefore contribute to maintain a certain degree of population connectivity and persistence regardless of habitat heterogeneity.

  14. Influence of waves and horseshoe crab spawning on beach morphology and sediment grain-size characteristics on a sandy estuarine beach

    USGS Publications Warehouse

    Jackson, N.L.; Nordstrom, K.F.; Smith, D.R.

    2005-01-01

    The effects of wave action and horseshoe crab spawning on the topography and grain-size characteristics on the foreshore of an estuarine sand beach in Delaware Bay, New Jersey, USA were evaluated using data collected over six consecutive high tides. Data were gathered inside and outside a 25 m long exclosure constructed to create a control area free of disturbance by crabs. The density of crabs in the swash zone outside the exclosure was 8??1 organisms m-2. The maximum depth of sediment activation on the upper foreshore where spawning occurred was 0??103 m during periods characterized by low significant wave heights: < 0??08 m. This depth is greater than the depth of activation by waves alone during moderate significant wave heights of 0??16 - 0??18 m but less than the maximum depth (0??127 m) recorded when spawning occurred during periods of moderate wave heights. Spawning, combined with moderate wave heights, creates a concave upper foreshore that is similar to the type of profile change that occurs during storms, thus lowering the wave-energy threshold for morphological response. Spawning during low wave heights increases the mean grain size and sorting of surface sediments caused by the addition of gravel to the swash. Sedimentological differences are most pronounced on the upper foreshore, and data from this location may be most useful when using grain-size characteristics to interpret the effect of spawning in the sedimentary record. Depths of sediment reworking by horseshoe crabs can be greater than those by subsequent storm waves, so evidence of spawning can be preserved on non-eroding beaches. Greater depth of activation by horseshoe crab spawning than by waves alone, even during moderate-energy conditions, reveals the importance of crab burrowing in releasing eggs to the water column and making them available for shore birds. ?? 2005 International Association of Sedimentologists.

  15. Delivery and movement of horseshoe crab eggs (Limulus polyphemus) in the breaking waves and swash uprush of an estuarine foreshore

    NASA Astrophysics Data System (ADS)

    Jackson, Nancy L.; Nordstrom, Karl F.; Smith, David R.; Saini, Sherestha

    2014-01-01

    Knowledge of conditions for entrainment of eggs and larvae from beach spawning sites is critical in determining the likelihood that these food sources will be delivered to shorebirds. The exhumation of horseshoe crab eggs buried within the beach foreshore is a function of changes in wave and current velocities over a tidal cycle. This field study was conducted to evaluate the temporal constraints to egg release at two different locations across the foreshore of a sandy estuarine beach in Delaware Bay, New Jersey. Wind, wave, current characteristics, beach change and eggs in transport were sampled over two tidal cycles. Egg counts were determined using four colors of dyed-egg tracers placed as point sources 5 and 10 m bayward of the expected upper limit of swash. Tracer recovery varied from 1% to 18% of the tracer eggs buried. Wave heights were relatively low (instrumented Hs = 0.09-0.17 m) but with long periods (5.6-8.8 s). Results reveal that egg release is discontinuous and occurs in pulses when the swash and breakers migrate across the injection points on the rising tide and when the breakers migrate past the injection points during the falling tide. A lack of tracer at the upper (5 m) injection point after early stages of high tide is likely due to the maximum disturbance depth being achieved early, leaving no eggs within the swash boundary layer. Peaks in recovery of tracer initially buried at the lower (10 m) location after the breakers migrated up the foreshore well past the injection location are likely from eggs deposited in the wrack on the upper beach or reburied in the sediment near the upper limit of swash and remobilized by high swash uprushes. These results using point sources of tracer eggs suggest that the contribution of eggs from within the beach matrix is temporally variable across the foreshore. Most eggs are released during rising tide, but additional eggs can be released during falling tide if the depth of activation of the bed is greater

  16. Estuarine Food Webs

    EPA Science Inventory

    Estuaries provide habitat for abundant plants, animals and micro-organisms, ranging from microscopic plankton (bacteria, yeasts, algae, protozoa) to larger benthic and pelagic organisms (seagrass, clams, crabs, sea trout, pelicans and dolphins). Estuarine biota can be characteri...

  17. Laboratory trials reveal that exposure to extreme raining events prior to metamorphosis affect the post-settlement performance of an estuarine crab

    NASA Astrophysics Data System (ADS)

    Rey, Felisa; Silva Neto, Gina M.; Rosa, Rui; Queiroga, Henrique; Calado, Ricardo

    2015-03-01

    Meteorological forcing can impact planktonic communities, with extreme raining events promoting salinity decreases and triggering larval mortality in estuarine plankton. The present study evaluated how exposure to low salinities prior to metamorphosis of Carcinus maenas megalopae (last larval stage) may affect its ability to metamorphose and the post-metamorphosis performance of juvenile crabs. An extreme raining event that promoted a generalized decrease in salinity (from 25 to 10) in the whole water column of one of the main channels of a coastal lagoon was mimicked in the laboratory. Wild megalopae of C. maenas were collected and kept individually without any food at salinities of 10 or 25 (S10 or S25) until they either died or metamorphosed to the first crab instar (C1). Specimens metamorphosing in 5 days or less following their collection were labeled as early settlers (ES10 and ES25), while those taking more than 5 days were labeled as late settlers (LS10 and LS25). All newly metamorphosed crabs were kept individually until C5 at a salinity of 25 and fed ad libitum, with their intermolt periods and carapace width (CW) being recorded. Osmotic stress did not affect the survival or ability to metamorphose of C. maenas megalopae, with 89% of all larvae in both salinities being able to metamorphose. This result is supported by the ability of this larval stage to hyper-regulate. Nonetheless, an exposure of late settling megalopae to low salinities prior to metamorphosis promotes the occurrence of juvenile crabs with a smaller CW. The deleterious effects of exposing late settling megalopae to low salinities appears to be magnified during early benthic life, with C5 originating from treatment LS10 displaying a significantly smaller CW (4.87 ± 0.28 mm) and lower wet weight (WW) (28.95 ± 4.62 mg). On the other side, C5 originating from ES25 exhibited a significantly higher CW (5.90 ± 0.33 mm) and WW (50.89 ± 8.14 mg). The nutritional vulnerability experienced by

  18. Influence of the geologic and geomorphologic characteristics and of crab burrows on the interrelation between surface water and groundwater in an estuarine coastal wetland

    NASA Astrophysics Data System (ADS)

    Carol, Eleonora S.; Kruse, Eduardo E.; Pousa, Jorge L.

    2011-06-01

    SummaryThe interrelation between surface water and groundwater in intertidal flats is often studied through mathematical models. In many cases these models need to be supported by an integral analysis of the geologic, geomorphologic, hydrologic and biological characteristics of the environment that are to be obtained from field surveys. The marshy environment of the River Ajo in the Samborombon Bay wetland, Argentina, is a typical example of an estuarine coastal zone. Geologic and geomorphologic surveys were carried out, as well as measurements of surface water and groundwater level changes as a response of the aquifer to tidal forcing. The banks of the River Ajo are either scarped with storm flats, or mildly sloped with intertidal flats and numerous crab burrows. Sediments are mainly silty-clayey with low permeability, and lie over silty-sandy layers. At the erosion scarps the tidal wave enters the aquifer as a sub-horizontal flow through the pore space of the sediments. The tidal range in the aquifer depends on the lithological characteristics of the sediments and on the side changes of their hydraulic conductivity. The rise of the water table at high water and its subsequent fall are nearly sinusoidal, with a period similar to that of the tide at the river. At the intertidal flats, instead, the tidal wave enters the aquifer mainly as a sub-vertical flow through the crab burrows. As the crab burrows are not interconnected, they are not distinct pathways for preferential flow. Therefore, the groundwater flux into the river is very slow during low water, and the recovery of the water table takes a long time. The tidal influence upon the water table on both kinds of banks affects only a narrow strip of the aquifer. Not only are the characteristics of the marshy environment of the River Ajo representative of most of the Samborombon Bay wetland; they can also be extended to other similar coastal wetlands to help preserve these invaluable environments.

  19. Morphological and molecular evidence on the existence of a single estuarine and rocky intertidal acanthocephalan species of Profilicollis Meyer, 1931 (Acanthocephala: Polymorphidae) along the Atlantic and Pacific coasts of southern South America.

    PubMed

    Rodríguez, Sara M; Diaz, Julia I; D'Elía, Guillermo

    2017-03-23

    Profilicollis chasmagnathi Holcman-Spector, Mañé-Garzón & Dei-Cas, 1977 (Acanthocephala: Polymorphidae) has been reported to parasitise different grapsid species as intermediate hosts along the South Atlantic shores, i.e. Cyrtograpsus angulatus (Dana) and Neohelice granulata (Dana) in Uruguay and Cyrtograpsus altimanus (Rathbun) in Argentina. Larvae of a similar acanthocephalan described as Profilicollis antarcticus Zdzitowiecki, 1985 were recorded in the crab Hemigrapsus crenulatus (Milne-Edwards) from an estuarine habitat on the Southeast Pacific shore in Chile. Earlier studies have questioned the specific assignation of the Chilean estuarine populations of Profilicollis Meyer, 1931. The aim of this study was to re-examine the identification of these acanthocephalans by means of morphological and molecular analyses of cystacanths of Profilicollis spp. gathered from C. angulatus, N. granulata, C. altimanus and H. crenulatus. Our analyses showed that a single species of Profilicollis, P. chasmagnathi, parasitises these four crab species. The assessment of specimens from the South Shetlands Islands, the type-locality of P. antarcticus, is needed before formally proposing that P. antarcticus is a junior subjective synonym of P. chasmagnathi.

  20. Comparison of sediment grain size characteristics on nourished and un-nourished estuarine beaches and impacts on horseshoe crab habitat, Delaware Bay, New Jersey

    USGS Publications Warehouse

    Jackson, N.L.; Smith, D.R.; Nordstrom, K.F.

    2005-01-01

    This study was undertaken to determine whether nourished and un-nourished estuarine beaches have conspicuous differences in sediment size and sorting that could affect their value as habitat for horseshoe crabs. Comparisons are made of beach profiles and sediment samples gathered at 0.15 m and 0.30 m depths on the backshore, at spring tide elevation, neap tide elevation, and the lower foreshore on 5 un-nourished and 3 nourished beaches in Delaware Bay, where tidal range is <2.0 m. The backshore is at least 0.5 m higher on the recently nourished beaches than on a nearby un-nourished beach reworked by storm waves. Nourishing these beaches to elevations higher than natural overwash heights will restrict natural evolution of the upper beach. Sediments at spring tide elevation on un-nourished sites average 0.72 mm in diameter at 0.15 m depth and 0.67 mm at 0.30 m depth.The similarity in size implies a relatively deep active layer in the zone of maximum cut and fill associated with cyclic profile change during low frequency, high magnitude storms. Sedimentary changes at neap tide elevation may be influenced more by depth of activation by waves than by cycles of deposition and erosion. Sediment at 0.15 m depth at spring and neap locations on the foreshore of nourished beaches is finer (0.51 mm) and better sorted (0.82 phi) than at 0.30 m depth (0.91 mm, 1.38 phi), implying that waves have not reworked the deeper sediments. Differences in sediment characteristics at depth may persist on eroding nourished beaches, where unreworked fill is close to the surface. Sediment texture influences horseshoe crab egg viability and development. Lower rates of water movement through the foreshore and greater thickness of the capillary fringe on nourished sites suggests that greater moisture retention will occur where horseshoe crabs bury eggs and may provide more favorable conditions for egg development, but the depth of these conditions will not be great on a recently nourished beach

  1. Temporal genetic homogeneity among shore crab (Carcinus maenas) larval events supplied to an estuarine system on the Portuguese northwest coast

    PubMed Central

    Domingues, C P; Creer, S; Taylor, M I; Queiroga, H; Carvalho, G R

    2011-01-01

    Despite the importance of larval biology in the life histories of many marine animals, relatively little information exists on the dynamics and genetic composition of larval cohorts. The supply of megalopae larvae of the shore crab, Carcinus maenas, was measured on a daily basis during 8 months spread along two larval periods (2006 and 2007) at the Ria de Aveiro estuary, on the Portuguese northwest coast. A total of 10 microsatellite DNA loci were employed to explore the genetic structure, variability and relatedness of temporally distinct megalopal events, selected from the major pulses of supply. Larval variation was also compared genetically with that of a previously studied adult crabs sample, at the same loci, collected in 2006 and 2007 along the Iberian Peninsula. Results revealed a lack of genetic differentiation and identical diversity levels among larval events over time. No evidence of reduced genetic diversity between megalopae relative to the diversity assessed from the pooled sample of adults was found. Moreover, there was no evidence of any family relatedness among larvae from temporal events. The results obtained for C. maenas contradict predictions made by the sweepstakes reproduction hypothesis, in which large variance in reproductive success is expected, which is presumably detectable as sharp genetic discontinuities among separate larval events. Data here indicate conversely a high degree of temporal genetic stability among larval supply to a given estuary under variable oceanographic conditions, consistent with the hypothesis that sampled larvae were drawn from a large number of adults that do not differ in reproductive success. PMID:20959862

  2. Transport of horseshoe crab eggs by waves and swash on an estuarine beach: Implications for foraging shorebirds

    NASA Astrophysics Data System (ADS)

    Nordstrom, Karl F.; Jackson, Nancy L.; Smith, David R.; Weber, Richard G.

    2006-11-01

    The abundance of horseshoe crab eggs in the swash zone and remaining on the beach after tide levels fall was evaluated to identify how numbers of eggs available to shorebirds differ with fluctuations in spawning numbers of horseshoe crabs, wave energies and beach elevation changes. Field data were gathered 1-6 June 2004 at Slaughter Beach on the west side of Delaware Bay, USA. Counts of spawning crabs and process data from a pressure transducer and an anemometer and wind vane were related to number of eggs, embryos and larvae taken at depth and on the surface of the foreshore and in the active swash zone using a streamer trap. Beach elevation changes and depths of sediment activation were used to determine the potential for buried eggs to be exhumed by waves and swash. Mean significant wave heights during high water levels ranged from 0.08 to 0.40 m. Spawning counts were low (50-140 females km -1) when wave heights were low; no spawning occurred when wave heights were high. Vegetative litter (wrack) on the beach provides local traps for eggs, making more eggs available for shorebirds. Accumulation of litter on days when wave energy is low increases the probability that eggs will remain on the surface. High wave energies transport more eggs in the swash, but these eggs are dispersed or buried, and fewer eggs remain on the beach. Peaks in the number of eggs in the swash uprush occur during tidal rise and around time of high tide. The number of eggs in transport decreases during falling tide. Many more eggs move in the active swash zone than are found on the beach after water level falls, increasing the efficiency of bird foraging in the swash. Greater numbers of eggs in the swash during rising tide than falling tide and fewer eggs at lower elevations on the beach, imply that foraging becomes less productive as the tide falls and may help account for the tendency of shorebirds to feed on rising tides rather than on falling or low tides on days when no spawning occurs.

  3. Transport of horseshoe crab eggs by waves and swash on an estuarine beach: Implications for foraging shorebirds

    USGS Publications Warehouse

    Nordstrom, K.F.; Jackson, N.L.; Smith, D.R.; Weber, R.G.

    2006-01-01

    The abundance of horseshoe crab eggs in the swash zone and remaining on the beach after tide levels fall was evaluated to identify how numbers of eggs available to shorebirds differ with fluctuations in spawning numbers of horseshoe crabs, wave energies and beach elevation changes. Field data were gathered 1-6 June 2004 at Slaughter Beach on the west side of Delaware Bay, USA. Counts of spawning crabs and process data from a pressure transducer and an anemometer and wind vane were related to number of eggs, embryos and larvae taken at depth and on the surface of the foreshore and in the active swash zone using a streamer trap. Beach elevation changes and depths of sediment activation were used to determine the potential for buried eggs to be exhumed by waves and swash. Mean significant wave heights during high water levels ranged from 0.08 to 0.40 m. Spawning counts were low (50-140 females km-1) when wave heights were low; no spawning occurred when wave heights were high. Vegetative litter (wrack) on the beach provides local traps for eggs, making more eggs available for shorebirds. Accumulation of litter on days when wave energy is low increases the probability that eggs will remain on the surface. High wave energies transport more eggs in the swash, but these eggs are dispersed or buried, and fewer eggs remain on the beach. Peaks in the number of eggs in the swash uprush occur during tidal rise and around time of high tide. The number of eggs in transport decreases during falling tide. Many more eggs move in the active swash zone than are found on the beach after water level falls, increasing the efficiency of bird foraging in the swash. Greater numbers of eggs in the swash during rising tide than falling tide and fewer eggs at lower elevations on the beach, imply that foraging becomes less productive as the tide falls and may help account for the tendency of shorebirds to feed on rising tides rather than on falling or low tides on days when no spawning occurs

  4. Fluctuations of biochemical constituents and marker enzymes as a consequence of naphthalene toxicity in the edible estuarine crab Scylla serrata.

    PubMed

    Vijayavel, K; Balasubramanian, M P

    2006-01-01

    The sublethal effects of naphthalene on protein, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), carbohydrates, lipids, and certain marker enzymes such as phosphatases, transaminases, and lactate dehydrogenase were studied in hepatopancreas, hemolymph, and ovary in the edible crab Scylla serrata. The results revealed that there was overall decrease in total protein, total DNA, total RNA, free sugar, glycogen, protein-bound sugars, neutral lipid, glycolipid, and phospholipid in the test samples compared to control. Similarly all the marker enzymes (acid phosphatase, alkaline phosphatase, aspartate transaminase, alanine transaminase, and lactate dehydrogenase) were decreased in hepatopancreas and ovary. On the other hand, in hemolymph, the activities of marker enzymes were increased. The results were tested statistically and interpreted accordingly.

  5. Hard-shell mating in Neohelice granulata: the role of ecdysone in female receptivity and mate attraction.

    PubMed

    Sal Moyano, María P; Luppi, Tomás; Medesani, Daniel A; McLay, Colin L; Rodríguez, Enrique M

    2017-03-01

    Most brachyuran females become receptive during the intermolt period, a condition considered "derived". However, as far as we know, studies testing the existence and function of pheromones in decapods are based on species which have mating linked to molting, a condition considered as "ancestral". For the first time, we studied some physiological and morphological processes involved in Neohelice granulata intermolt female crabs becoming receptive and potentially attracting males. We found that receptive females have mobile vulvae opercula due to a softening process of the cuticle hinge which showed lower calcium levels compared to the hinge of unreceptive females. Local softening of the hinge was stimulated by a low concentration of ecdysone during the intermolt period. A putative pheromone liberated by receptive females to attract males is presumed to be released through the mobile vulvae and not through the urine.

  6. A baseline study of the metallothioneins induction and its reversibility in Neohelice granulata from the Bahía Blanca Estuary (Argentina).

    PubMed

    Buzzi, N S; Marcovecchio, J E

    2016-11-15

    Contamination by heavy metals causes serious effects in marine systems. Nowadays, the combination of chemical and biological data is recommended in monitoring programs. Metallothioneins (MT) are early-warning signals of metal exposure and are widely used in biomonitoring. The present research evaluates the heavy metals levels in sediments and the MT synthesis in the crab Neohelice granulata from the Bahía Blanca Estuary (BBE). Then, the recovery capabilities of N. granulata followed by a depuration phase are assessed. Results demonstrate a slow decline in the level of metals in the study area. In relation to MT, female crabs showed elevated MT when compared to males. Furthermore, MT synthesis diminished after the depuration phase. These data constitute the first MT information in organisms from the BBE and may be considered as baseline for future studies in this matter. Although pollution level found was low, further biomonitoring considering both types of data is recommended.

  7. Habitat-related differences in the pre-copulatory guarding and copulation behavior of Neohelice granulata (Brachyura, Grapsoidea, Varunidae)

    NASA Astrophysics Data System (ADS)

    Sal Moyano, María P.; Gavio, María A.; McLay, Colin L.; Luppi, Tomás

    2014-03-01

    Mating behavior strategies of brachyuran crabs are flexible depending on the habitat and social context. We evaluate pre-copulatory guarding in Neohelice granulata and describe the unusual copulatory behavior. Laboratory experiments were conducted to test whether factors such as male size, presence of burrows, a male-biased operational sex ratio (OSR) and female mating history affect the copulation duration in two different study areas. Females initiated a searching behavior approximately 20-26 h before they became receptive by assessing large male burrows and displaying a courtship behavior (“flirting”) in its entrance. Once the female entered inside the male burrow, pre-copulatory guarding was observed until the female became receptive and successful copulation occurred immediately after. This species shows some very unusual copulatory behavior involving eyestalk grasping not seen in any other varunid crab. The copulation duration was independent of male size and the presence of burrows, although it was dependent on the study area, the OSR and the female mating history. Thus, copulation duration is a flexible character in this species which varies with habitat and biological factors such as mating history and sex ratio.

  8. Good Crab, Bad Crab

    EPA Science Inventory

    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...

  9. Effects of Underwater Turbine Noise on Crab Larval Metamorphosis.

    PubMed

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

    2016-01-01

    The development of marine tidal turbines has advanced at a rapid rate over the last decade but with little detailed understanding of the potential noise impacts on invertebrates. Previous research has shown that underwater reef noise plays an important role in mediating metamorphosis in many larval crabs and fishes. New research suggests that underwater estuarine noise may also mediate metamorphosis in estuarine crab larvae and that the noise emitted from underwater tidal and sea-based wind turbines may significantly influence larval metamorphosis in estuarine crabs.

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

    PubMed

    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.

  11. Differences in the escape response of a grapsid crab in the field and in the laboratory.

    PubMed

    Hemmi, Jan M; Tomsic, Daniel

    2015-11-01

    Escape behaviours of prey animals are frequently used to study the neural control of behaviour. Escape responses are robust and fast, and can be reliably evoked under both field and laboratory conditions. Many escape responses are not as simple as previously suggested, however, and are often modulated by a range of contextual factors. To date it has been unclear to what extent behaviours studied in controlled laboratory experiments are actually representative of the behaviours that occur under more natural conditions. Here, we have used the model species Neohelice granulata, a grapsid crab, to show that there are significant differences between the crabs' escape responses in the field compared with those previously documented in laboratory experiments. These differences are consistent with contextual adjustments such as the availability of a refuge and have clear consequences for understanding the crabs' neural control of behaviour. Furthermore, the methodology used in this study mirrors the methodology previously used in fiddler crab research, allowing us to show that the previously documented differences in escape responses between these grapsid species are real and substantial. Neohelice granulata's responses are delayed and more controlled. Overall, the results highlight the adaptability and flexibility of escape behaviours and provide further evidence that the neural control of behaviour needs to be addressed in both the laboratory and field context.

  12. Physical and chemical changes in the foreshore of an estuarine beach: Implications for viability and development of horseshoe crab Limulus polyphemus eggs

    USGS Publications Warehouse

    Jackson, N.L.; Smith, D.R.; Nordstrom, K.F.

    2008-01-01

    Knowledge of conditions that favor development of eggs is important for management of species whose population growth is sensitive to early life history survival. Viability and development of the eggs of horseshoe crabs Limulus polyphemus on a sand and gravel beach were evaluated using data gathered on Delaware Bay, USA, from 18 May to 19 June 2004. Eggs were transplanted to pouches and buried in the foreshore for up to 6 wk. Viability and developmental stage were estimated as a function of oxygen and temperature gradients across the foreshore. These gradients were related to the characteristics of the intertidal foreshore sediments, beach water table changes, and frequency of inundation due to tide and swash/backwash processes. Results demonstrate the importance of interstitial temperature for development to larvae and the passive role of sediment characteristics on moisture retention and temperature. Percentage of eggs remaining in egg stage was similar across the foreshore, but more eggs developed to embryos at 0.45 of foreshore width, where moisture and gravel content were greater and interstitial temperature was lower. More eggs developed to larvae at 0.60 and 0.75 of foreshore width, where moisture and gravel content were less but interstitial temperature was higher. The beach above 0.75 of foreshore width came under the influence of wave action or full tidal inundation only during high wave heights or spring tides, and pouches at 0.75 of foreshore width were inundated only 19% of the time. Periodic wetting at this elevation did not reduce overall viability of the eggs. High wave energy events resulted in sediment activation depths to pouches at 0.30 of foreshore width, where loss of eggs due to wave activation was the most important control on the development of eggs. ?? Inter-Research 2008.

  13. Vicissitudes of oxidative stress biomarkers in the estuarine crab Scylla serrata with reference to dry and wet weather conditions in Ennore estuary, Tamil Nadu, India.

    PubMed

    Ragunathan, M G

    2017-03-15

    The primary objective of this study was to understand the impact of monsoon and summer seasons on the Polychlorinated Biphenyls (PCB's) and petroleum hydrocarbon compounds (PHC's) load in Ennore estuary and how the physiological response of estuarine Scylla serrata inhabiting in this estuary changed with reference to antioxidant defense. Seasonal levels of PCB's and PHC's were assessed in the water along with their bioaccumulation in gills, hemolymph, hepatopancreas and ovary of S. serrata. Concentration of PCB's and PHC's in water and their bioaccumulation was found to be higher in summer season when compared to monsoon season. Enzymic antioxidant assays [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione-S-transferase (GST)]; non-enzymic antioxidant assays [glutathione (GSH), vitamin C, vitamin E] and macromolecular alterations [membrane lipid peroxidation (LPO), and DNA Damage (strand breaks)] were assessed in the gills, hemolymph and hepatopancreas of S. serrata. There was a significant (p<0.05) upregulation in lipid peroxidation activity and DNA damage activity collected during the summer season when compared to the pre- and post-monsoon seasons. On the contrary, the enzymic and non-enzymic antioxidants exhibited significant (p<0.05) down regulation in the gills, hemolymph, hepatopancreas and ovary of S. serrata. Oxidative stress biomarkers represented a significant (p<0.05) maximum in gills when compared to hemolymph and hepatopancreas of S. serrata. Present study provided scientific evidences of how the antioxidant defense status of S. serrata responded to PCB's and PAH's stress with reference to seasonal vicissitudes, which indirectly represented the environmental health conditions of the estuary.

  14. Receptivity of female Neohelice granulata (Brachyura, Varunidae): different strategies to maximize their reproductive success in contrasting habitats

    NASA Astrophysics Data System (ADS)

    Sal Moyano, María Paz; Luppi, Tomás; Gavio, María Andrea; Vallina, Micaela; McLay, Colin

    2012-12-01

    The extent of the receptive period may determine the mating strategies employed by female crabs to obtain mates. Here, we studied the receptivity of female Neohelice granulata (Dana, 1851) in the laboratory, including the form of the vulvae and the anatomy of the seminal receptacle (SR). We examined the factors that influence the duration of receptivity by comparing two populations inhabiting contrasting habitats: Mar Chiquita Coastal lagoon (MCL), which is an oligo-polyhaline estuary, and San Antonio Oeste (SAO), which is an eu-hyperhaline marine bay. Non-receptive females have immobile vulva opercula, while receptive females have mobile opercula. Histological sections of the SR showed that the degree of epithelium secretions was associated with the receptive stage of females, and they may be involved in the maintenance of viable sperm and in the dehiscence of spermatophores. The existence of a special tissue at the junction of the oviduct and the SR was described and proposed as an internal mechanism influencing the timing of ovulation. The duration of receptivity was dependent on the SR load and the capacity to lay eggs. Thus, females with empty SR exhibited longer receptivity and did not lay eggs, while those with full SR exhibited shorter receptivity and always laid eggs. Interpopulation differences showed that females from SAO had shorter receptivity and heavier SR and laid eggs more frequently than females from MCL. Based on our results, we suggest that N. granulata females can adjust the duration of their receptivity and control the moment of fertilization according to different internal mechanisms related to the morphology of the vulvae, the fullness of the SR and anatomical attributes of the SR. An important consequence of this control is greater sperm competition. The extent of the receptive period and the number of times that a female could become receptive in a single reproductive season may also depend on the habitat characteristics.

  15. Horseshoe crabs.

    PubMed

    Botton, Mark L

    2002-10-01

    Horseshoe crabs are one of evolution's success stories. These living fossils have contributed immensely to biomedical research, and their eggs are a critical link in the migration cycle of New World waders (shorebirds) Can they endure threats posed by a growing commercial fishery and the loss of essential spawning habitats?

  16. ESTUARINE HABITAT RESTORATION

    SciTech Connect

    Thom, Ronald M.; Borde, Amy B.

    2015-09-01

    Restoring estuarine habitats generally means repairing damages caused by humans and natural forces. Because of the extensive human occupation, development, and use of coastal areas for centuries, the extensive estuarine habitats have been either destroyed or significantly impaired.

  17. Seasonal effects of leached mirex on selected estuarine animals.

    PubMed

    Tagatz, M E; Borthwick, P W; Forester, J

    1975-01-01

    Four 28-day seasonal experiments were conducted using selected estuarine animals in outdoor tanks that received continuous flow of mirex-laden water. Mirex (dodecachlorooctahydro-1,3,4-metheno-2H-cyclobuta [cd] pentalene) leached from fire ant bait (0.3% mirex) by fresh water and then mixed with salt water was toxic to blue crabs (Callinectes sapidus), pink shrimp (Penaeus duorarum), and grass shrimp (Palaemonetes pugio) but not to sheepshead minnows (Cyprinodon variegatus), at concentrations less than 0.53 mug/L in water. The amount of leaching was greatest in summer and least in spring. Greatest mortality occurred in summer at the highest water temperature and concentration of mirex; least mortality occurred in spring at the next to the lowest temperature and at the lowest concentration. Earliest deaths of blue crabs occurred after six days of exposure and shrimps after two days. Small juvenile crabs were more sensitive to leached mirex than were large juveniles. Mirex did not appear to affect growth or frequency of molting in crabs. All exposed animals concentrated mirex. Among animals that survived for 28 days, sheepshead minnows concentrated mirex 40,800X above the concentration in the water, blue crabs 2,300X, pink shrimp 10,000X, and grass shrimp 10,800X. Sand substrata contained mirex up to 770X that in the water. Most control and exposed animals in samples examined histologically had normal tissues, but alteration in gills of some exposed fish and natural pathogens in some exposed and control crabs and shrimp were observed. The experiments demonstrated that mirex can be leached from bait by fresh water, concentrated by estuarine organisms, and can be toxic to crabs and shrimps.

  18. Effects of extracts from the cyanobacterium Microcystis aeruginosa on ion regulation and gill Na+,K+-ATPase and K+-dependent phosphatase activities of the estuarine crab Chasmagnathus granulata (Decapoda, Grapsidae).

    PubMed

    Vinagre, T M; Alciati, J C; Yunes, J S; Richards, J; Bianchini, A; Monserrat, J M

    2002-01-01

    Recent discoveries indicate that microcystins affect enzymes, such as Na(+),K(+)-ATPase, involved in ion regulation of aquatic animals, through K(+)-dependent phosphatase inhibition. In vitro studies showed the inhibitory effect of Microcystis aeruginosa extracts on Na(+),K(+)-ATPase and K(+)-dependent phosphatase activities in gills of Chasmagnathus granulata (Decapoda, Grapsidae). Extracts of M. aeruginosa were prepared from lyophilized or cultures cells of the cyanobacterium. For lyophilized cells, IC(50) values were estimated as 0.46 microg/L (95% confidence interval [CI]=0.40-0.52 microg/L) and 1.31 microg/L (95% CI=1.14-1.51 microg/L) for Na(+),K(+)-ATPase and K(+)-dependent phosphatase, respectively. However, extracts prepared from cultured cells presented a much lower inhibitory potency against both enzymes. Gas chromatography revealed long-chain fatty acids in the lyophilized cell extracts, indicating that they are in part responsible for the enzyme inhibition. In vivo studies showed that the toxin inhibited Na(+),K(+)-ATPase activity in anterior gills, whereas an increased augmented activity of glutathione-S-transferase was observed in both kind of gills, indicating that the crab has increased its ability to conjugate the toxin. No significant differences in hemolymph sodium or chloride concentration were detected. This result is in agreement with the lack of effects of microcystin on Na(+),K(+)-ATPase activity of posterior (osmoregulating) gills.

  19. Predicting habitat associations of five intertidal crab species among estuaries

    NASA Astrophysics Data System (ADS)

    Vermeiren, Peter; Sheaves, Marcus

    2014-08-01

    Intertidal crab assemblages that are active on the sediment surface of tropical estuaries during tidal exposure play an important role in many fundamental ecosystem processes. Consequently, they are critical contributors to a wide range of estuarine goods and services. However, a lack of understanding of their spatial organization within a large landscape context prevents the inclusion of intertidal crabs into generally applicable ecological models and management applications. We investigated spatial distribution patterns of intertidal crabs within and among eight dry tropical estuaries spread across a 160 km stretch of coast in North East Queensland, Australia. Habitat associations were modelled for five species based on photographic sampling in 40-80 sites per estuarine up- and downstream component: Uca seismella occurred in sites with little structure, bordered by low intertidal vegetation; Macrophthalmus japonicus occupied flat muddy sites with no structure or vegetation; Metopograpsus frontalis and Metopograpsus latifrons occupied sites covered with structure in more than 10% and 25% respectively. Finally, both Metopograpsus spp. and Metopograpsus thukuhar occupied rock walls. Habitat associations were predictable among estuaries with moderate to high sensitivity and low percentages of false positives indicating that simple, physical factors were adequate to explain the spatial distribution pattern of intertidal crabs. Results provide a necessary first step in developing generally applicable understanding of the fundamental mechanisms driving spatial niche organization of intertidal crabs within a landscape context.

  20. Polychlorinated biphenyls in blue crabs from South Carolina

    SciTech Connect

    Marcus, J.M.; Mathews, T.D.

    1987-11-01

    Blue crabs are important members of the estuarine food web due to their numbers and their multiple roles as scavengers, predators and prey. Because of their omnivorous feeding characteristics, wide distribution an close association with bottom sediments, the potential exists for blue crabs to bioaccumulate pollutants residing in those sediments as has been shown for fiddler crabs. It follows that human health risk upon consumption of such crabs and biomagnification through the food web become primary concerns. During the spring of 1985, commercial crab fishermen in Beaufort County, South Carolina contacted the South Carolina Wildlife and Marine Resources Department (SCWMRD) concerning their perceptions of significantly declining catch rates in the Campbell Creek-Whale Branch area. Using knowledge of previously documented elevated polychlorinated biphenyls (PCB) levels in the sediments of the upper portion of Campbell Creek, the SCWMRD initiated analysis of crab tissue from the area to ascertain the body burdens of PCBs. Initial screening results indicated potentially significant levels of PCBs in blue crabs at which time, SCWMRD contacted the SC Department of Health and Environmental Control (SCDHEC) for more intensive study and definition of the situation. The work reported here was conducted between June and October 1985.

  1. EFFECTS OF FENOXYCARB EXPOSURE ON COMPLETE LARVAL STAGES OF THE XANTHID CRAB, RHITHROPANOPEUS HARRISII

    EPA Science Inventory

    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 pa...

  2. Crab regulation of cross-ecosystem resource transfer by marine foraging fire ants.

    PubMed

    Garcia, Erica A; Bertness, Mark D; Alberti, Juan; Silliman, Brian R

    2011-08-01

    Permeability of boundaries in biological systems is regulated by biotic and/or abiotic factors. Despite this knowledge, the role of biotic factors in regulating resource transfer across ecosystem boundaries has received little study. Additionally, little is known about how cross-ecosystem resource transfer affects source populations. We used experiments, observations and stable isotopes, to evaluate: (1) the proportion of intertidal-foraging black fire ant (Solenopsis richteri) diet derived from marine sources, (2) how black fire ant cross-ecosystem resource transfer is altered by the dominant bioengineer in the intertidal, a burrowing crab (Neohelice granulata), (3) the top-down impact of these terrestrial ants on a marine resource, and (4) the effect of marine resources on recipient black fire ants. We found that more than 85% of the black fire ant diet is derived from marine sources, the number of intertidal foraging ants doubles in the absence of crab burrows, and that ants cause a 50% reduction in intertidal polychaetes. Also, ant mound density is three times greater adjacent to marine systems. This study reveals that cross-ecosystem foraging terrestrial ants can clearly have strong impacts on marine resources. Furthermore, ecosystem engineers that modify and occupy habitat in these ecosystem boundaries can strongly regulate the degree of cross-ecosystem resource transfer and resultant top down impacts.

  3. Pubic Lice (Crabs)

    MedlinePlus

    ... Surgery? A Week of Healthy Breakfasts Shyness Pubic Lice (Crabs) KidsHealth > For Teens > Pubic Lice (Crabs) A A A en español Ladilla (piojo del pubis) What Are They? Pubic lice are tiny insects that can crawl from the ...

  4. Estuarine Food for Thought

    NASA Astrophysics Data System (ADS)

    M�ller-Solger, A. B.; M�ller-Navarra, D. B.

    2002-12-01

    Recent research in animal and human nutrition has shown the importance of long-chain polyunsaturated fatty acids (LC-PUFA) such as the n-3 LC-PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These LC-PUFA are needed for healthy development and functioning of the nervous and vascular systems. De novo synthesis or elongation to LC-PUFA in animals is inefficient at best; thus sufficient amounts of these PUFA must be supplied by food sources. Algae, especially diatoms, dinoflagellates, and cryptophytes, are the quantitatively most important producers of EPA and DHA. These types of algae often dominate estuarine producer communities. The upper San Francisco Estuary is no exception, and we found its LC-PUFA-rich phytoplankton biomass, but not the quantitatively prevalent terrestrial plant detritus, to be highly predictive of zooplankton (Daphnia) growth. In contrast, in freshwater lakes dominated by relatively LC-PUFA-poor phytoplankton, EPA, not total phytoplankton biomass, best predicted Daphnia growth. The commonly high abundance of LC-PUFA-rich algae in estuaries may help explain the high trophic efficiencies in these systems and resulting high consumer production. Moreover, LC-PUFA-rich estuarine food resources may also provide essential nutrition and associated health and evolutionary benefits to land-dwelling consumers of such foods, including humans. Ensuring LC-PUFA-rich, uncontaminated estuarine production is thus an important goal for estuarine restoration and a convincing argument for estuarine conservation.

  5. Sublethal Toxicity of Crude Oil Exposure in The Blue Crab, Callinectes sapidus, at Two Life History Stages.

    PubMed

    Giltz, Sarah M; Taylor, Caz M

    2017-02-01

    The 2010 Deepwater Horizon oil spill occurred during peak spawning season for many Gulf of Mexico fish and invertebrates. Early life stages of important fishery species were at risk to encounter crude oil. In this study, we investigated the effect of crude oil exposure on two life stages of the blue crab (Callinectes sapidus). We tested the effects of oil exposure on the survival and growth of larval (pelagic) and juvenile (estuarine) blue crabs as well as the effects of oil on the molt frequency of juveniles. Larval crabs exposed to crude oil showed no discernable growth or mortality differences when compared to non-exposed controls. Juvenile crabs exposed to oil also showed no differences in size but exhibited increased intermolt duration (time between molts). Our study suggests that different life-stages may respond differently when exposed to crude oil and that oil exposure negatively affects growth rate of juvenile blue crabs.

  6. Organization of columnar inputs in the third optic ganglion of a highly visual crab.

    PubMed

    Bengochea, Mercedes; Berón de Astrada, Martín

    2014-01-01

    Motion information provides essential cues for a wide variety of animal behaviors such as mate, prey, or predator detection. In decapod crustaceans and pterygote insects, visual codification of object motion is associated with visual processing in the third optic neuropile, the lobula. In this neuropile, tangential neurons collect motion information from small field columnar neurons and relay it to the midbrain where behavioral responses would be finally shaped. In highly ordered structures, detailed knowledge of the neuroanatomy can give insight into their function. In spite of the relevance of the lobula in processing motion information, studies on the neuroarchitecture of this neuropile are scant. Here, by applying dextran-conjugated dyes in the second optic neuropile (the medulla) of the crab Neohelice, we mass stained the columnar neurons that convey visual information into the lobula. We found that the arborizations of these afferent columnar neurons lie at four main lobula depths. A detailed examination of serial optical sections of the lobula revealed that these input strata are composed of different number of substrata and that the strata are thicker in the centre of the neuropile. Finally, by staining the different lobula layers composed of tangential processes we combined the present characterization of lobula input strata with the previous characterization of the neuroarchitecture of the crab's lobula based on reduced-silver preparations. We found that the third lobula input stratum overlaps with the dendrites of lobula giant tangential neurons. This suggests that columnar neurons projecting from the medulla can directly provide visual input to the crab's lobula giant neurons.

  7. Spatial dynamics of large-scale, multistage crab (Callinectes sapidus) dispersal: Determinants and consequences for recruitment

    USGS Publications Warehouse

    Etherington, L.L.; Eggleston, D.B.

    2003-01-01

    We assessed determinants and consequences of multistage dispersal on spatial recruitment of the blue crab, Callinectes sapidus, within the Croatan, Albemarle, Pamlico Estuarine System (CAPES), North Carolina, U.S.A. Large-scale sampling of early juvenile crabs over 4 years indicated that spatial abundance patterns were size-dependent and resulted from primary post-larval dispersal (pre-settlement) and secondary juvenile dispersal (early post-settlement). In general, primary dispersal led to high abundances within more seaward habitats, whereas secondary dispersal (which was relatively consistent) expanded the distribution of juveniles, potentially increasing the estuarine nursery capacity. There were strong relationships between juvenile crab density and specific wind characteristics; however, these patterns were spatially explicit. Various physical processes (e.g., seasonal wind events, timing and magnitude of tropical cyclones) interacted to influence dispersal during multiple stages and determined crab recruitment patterns. Our results suggest that the nursery value of different habitats is highly dependent on the dispersal potential (primary and secondary dispersal) to and from these areas, which is largely determined by the relative position of habitats within the estuarine landscape.

  8. EFFECTS OF THE INSECT JUVENILE HORMONE AGONIST, METHOPRENE, ON FEMALE GROWTH AND REPRODUCTION IN THE GULF SAND FIDDLER CRAB.

    EPA Science Inventory

    Adult Uca panacea were collected from the shores of West Bay Point near Panama City, Florida, in late April of 2000. These crabs (250 females, 100 males per pond) were distributed randomly into six specially constructed estuarine ponds to determine the effects of field applicatio...

  9. Marine and Estuarine Pollution.

    ERIC Educational Resources Information Center

    Reish, Donald J.

    1978-01-01

    Presents a literature review of the effects of various pollutants on marine and estuarine organisms, covering publications of 1976-77. This review includes: (1) effects of pesticides, dredging, dumping, sludge, and petroleum hydrocarbons; and (2) diseases and tissue abnormalities. A list of 441 references is also presented. (HM)

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    Little is known about the effects of mud crabs population patterns on their exploitation. We used complementary approaches (experimental, fisher-based) to investigate how small-scale variations in density, size and sex-ratio related to the ecology of S. serrata may impact fishing practices in New Caledonia. Crabs were measured/sexed across 9 stations in contrasted mangrove systems between 2007 and 2009. Stations were described and classified in different kinds of mangrove forests (coastal, riverine, and estuarine); vegetation cover was qualitatively described at station scale. Annual catch was used as an indicator of fishing pressure. Middle-scale environmental factors (oceanic influence, vegetation cover) had significant contributions to crab density (GLM, 84.8% of variance), crab size and sex-ratio (< 30%). While small-scale natural factors contributed significantly to population structure, current fishing levels had no impacts on mud crabs. The observed, ecologically-driven heterogeneity of crab resource has strong social implications in the Pacific area, where land tenure system and traditional access rights prevent most fishers from freely selecting their harvest zones. This offers a great opportunity to encourage site-specific management of mud crab fisheries.

  11. Estuarine-Shelf Interactions,

    DTIC Science & Technology

    1986-01-01

    latter process occurs at the mouth of the Magothy strength of the flow rather than being specified a River, an estuary tributary to Chesapeake Bay...periods. It is also clear, Magothy in the immediate past. As the density though, that significant geographical variability front associated with the...Estuarine Coastal chemical hydrography of the Magothy River, ?tar. Sci., ’)(4), 485-496, 1977. Tech. Rep. XVIR, Ref. 59-2, Chesapeake bay Hachey, H. B

  12. The influence of insect juvenile hormone agonists on metamorphosis and reproduction in estuarine crustaceans.

    PubMed

    McKenney, Charles L

    2005-01-01

    Comparative developmental and reproductive studies were performed on several species of estuarine crustaceans in response to three juvenile hormone agonists (pyriproxyfen, methoprene and fenoxycarb). Larval development of the grass shrimp, Palaemonetes pugio, was greater than two orders of magnitude more sensitive to disruption by methoprene and fenoxycarb than was embryonic development. Developing larvae of the mud crab, Rhithropanopeus harrisii, exhibited reduced metamorphic success at lower concentrations of methoprene and pyriproxyfen than grass shrimp larvae. These responses suggest that the more rigidly controlled metamorphic process in crabs is more sensitive to compounds acting as endocrine disruptors than is the more flexible metamorphic pattern in shrimp. The final crab larval stage, the megalopa, was more sensitive to methoprene and fenoxycarb exposure than earlier zoeal stages. Mud crab larvae exposed to fenoxycarb had reduced biomass and lipid content, particularly triglycerides and sterols. Concentrations of fenoxycarb which reduced the reproductive capacity in single life-cycle exposures of the estuarine mysid, Americamysis bahia, were similar to those concentrations which inhibited metamorphosis in grass shrimp. Juvenile mysids released by exposed adults and reared through maturation without further exposure produced fewer young and had altered sex ratios (lower percentages of males) at lower parental-exposure concentrations than directly affected parental reproduction. These transgenerational responses may well be a product of irreversible effects during developmental exposures which become apparent following maturation and initiation of reproduction. These findings support using a functional approach as an appropriate screening procedure to evaluate potential environmental endocrine-disrupting chemicals in aquatic environments.

  13. Lack of transmission of Hematodinium sp. in the blue crab Callinectes sapidus through cannibalism.

    PubMed

    Li, Caiwen; Wheeler, Kersten N; Shields, Jeffrey D

    2011-10-06

    Hematodinium spp. are parasitic dinoflagellates of marine crustaceans. Outbreaks of Hematodinium sp. have impacted commercial landings of the blue crab Callinectes sapidus in the coastal bays of Virginia and Maryland (USA), with seasonal peaks in prevalence reaching 85%. The life cycle and transmission routes of the parasite in blue crabs are poorly understood. Cannibalism and waterborne transmission may be routes of transmission, although little conclusive evidence has been reported for these modes. We examined cannibalism as a route by a series of experiments wherein we repeatedly fed adult and juvenile crabs the tissues of crabs infected with Hematodinium. In each experiment, feeding was done 3 times over the course of 1 wk. Only 2 of 120 crabs were infected within 7 to 9 d after feeding, and these 2 were likely infected prior to the experimental exposures. Crabs inoculated with hemolymph from infected donors served as positive controls. They developed infections over 11 to 21 d, indicating that the Hematodinium sp. used in the cannibalism trials was infectious at the time of inoculation. Because amphipods also harbor Hematodinium-like infections, we fed tissues of infected crabs to the estuarine amphipod Leptocheirus plumulosus. Hematodinium DNA was detected in amphipods shortly after feeding, but not in animals held for longer periods, nor was it observed in histological preparations. Amphipods did not obtain infections by scavenging infected crab tissues. Our results show that Hematodinium sp. is not effectively transmitted through ingestion of diseased tissues, indicating that cannibalism may not be a major route of transmission for Hematodinium sp. in blue crabs.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

  15. Sediment dynamics modulated by burrowing crab activities in contrasting SW Atlantic intertidal habitats

    NASA Astrophysics Data System (ADS)

    Escapa, Mauricio; Perillo, Gerardo M. E.; Iribarne, Oscar

    2008-11-01

    Biogenic bottom features, animal burrows and biological activities interact with the hydrodynamics of the sediment-water interface to produce altered patterns of sediment erosion, transport and deposition which have consequences for large-scale geomorphologic features. It has been suggested that depending on the hydrodynamic status of the habitat, the biological activity on the bottom may have a variety of effects. In some cases, different bioturbation activities by the same organism can result in different consequences. The burrowing crab Neohelice granulata is the most important bioturbator at SW Atlantic saltmarshes and tidal plains. Because of the great variety of habitats that this species may inhabit, it is possible to compare its bioturbation effects between zones dominated by different hydrodynamic conditions. Internal marsh microhabitats, tidal creeks bottoms and basins, and open mudflats were selected as contrasting zones for the comparison on a large saltmarsh at Bahía Blanca Estuary (Argentina). Crab burrows act as passive traps of sediment in all zones, because their entrances remain open during inundation periods at high tide. Mounds are generated when crabs remove sediments from the burrows to the surface and become distinctive features in all the zones. Two different mechanisms of sediment transport utilizing mounds as sediment sources were registered. In the first one, parts of fresh mound sediments were transported when exposed to water flow during flooding and ebbing tide, with higher mound erosion where currents were higher as compared to internal marsh habitats and open mudflats. In the second mechanism, mounds exposed to atmospheric influence during low tide became desiccated and cracked forming ellipsoidal blocks, which were then transported by currents in zones of intense water flow in the saltmarsh edge. Sedimentary dynamics varied between zones; crabs were promoting trapping of sediments in the internal saltmarsh (380 g m -2 day -1) and

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

    PubMed

    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 (<0.5, 25 and 60‰ S) and oxygen consumption rates at different temperatures (15, 25 and 35°C) in U. rapax collected from localities along the coast of São Paulo State showing different histories of metal contamination (most contaminated Ilha Diana, Santos>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.

  17. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Pacific Northwest): Dungeness crab. [Cancer magister dana

    SciTech Connect

    Pauley, G.B.; Armstrong, D.A.; Heun, T.W.

    1986-08-01

    The Dungeness crab (Cancer magister) is found off the coasts of Washington, Oregon, and southern British Columbia, as well as in the estuarine waters of this geographic area. It is a shellfish highly prized and sought after by both commercialand sport fishermen. In Washington and Oregon, only male crabs may be retained by sport and commercial fishermen. Commercial crab catches are highly variable from year to year, but the catches from Washington and Oregon follow a very similar pattern. The highest sport catches take place on low tides ranging from -0.60 to -0.74 m. Dungeness crab go through a life cycle that involves several metamorphic stages: zoea, megalops, postlarval crab, and adult crab. Hatching success decreases as water temperature increases from 10 to 17/sup 0/C; the optimal temperature for larval crabs is between 10 and 14/sup 0/C. Salinity is not as important to egg development and hatching as temperature, but optimum hatching occurs at about 15 ppt.

  18. Acute toxicity of sodium metabisulphite on mangrove crab Ucides cordatus (Decapoda, Ucididae).

    PubMed

    Pedale, Adriana B; Fujimoto, Rodrigo Y; Santos, Rudã F B; Abrunhosa, Fernando A

    2012-12-01

    The sodium metabisulphite salt is usually used in shrimp culture to prevent black spot. Unfortunately the toxicological effect of this xenobiotic in decapod crabs is unknown. Thus, the present study aims to investigate the sodium metabisulphite LC(50) - 96 h in the mangrove species Ucides cordatus. Crabs were collected in the tidal creek margins in Bragança estuarine and were submitted to preliminary test (screening) and posterior definitive test. Crabs were exposed in five different concentrations and a control group in five replicates, two crabs per recipient (5 L) during 96 hours. A negative correlation was observed to sodium metabisulphite concentration in relation to dissolved oxygen and pH. At the end of the experiment were obtained the following mortality index in relation to sodium metabisulphite concentrations: 100% in 86.0 mg.L(-1), 74% in 62.0 mg.L(-1), 52% in 52.0 mg.L(-1), 44% in 38.0 mg.L(-1). The value of LC(50) - 96 h for U. cordatus was determinate at 42.58 mg.L(-1)/Na(2)S(2)O(5). The results strongly indicate that sodium metabisulphite is toxic for U. cordatus, and this crab could be used for biomonitoring the environmental impact.

  19. Crab Cavities for Linear Colliders

    SciTech Connect

    Burt, G.; Ambattu, P.; 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; /SLAC

    2011-11-08

    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.

  20. CRAB Cavity in CERN SPS

    SciTech Connect

    Kim, H.J.; Sen, T.; /Fermilab

    2010-05-01

    Beam collisions with a crossing angle at the interaction point are often necessary in colliders to reduce the effects of parasitic collisions which induce emittance growth and decrease beam lifetime. The crossing angle reduces the geometrical overlap of the beams and hence the luminosity. Crab cavity offer a promising way to compensate the crossing angle and to realize effective head-on collisions. Moreover, the crab crossing mitigates the synchro-betatron resonances due to the crossing angle. A crab cavity experiment in SPS is proposed as a proof of principle before deciding on a full crab-cavity implementation in the LHC. In this paper, we investigate the effects of a single crab cavity on beam dynamics in the SPS and life time.

  1. Bdellovibrios in Callinectus sapidus, the Blue Crab

    PubMed Central

    Kelley, Jacqueline I.; Williams, Henry N.

    1992-01-01

    Bdellovibrios were recovered from the gill tissue of all of 31 crabs sampled and from all samples of epibiota obtained from the ventral shell surface of 15 crabs. The results suggest that the blue crab is a reservoir for bdellovibrios. The association with crabs may be an important factor in the ecology of the bdellovibrios. PMID:16348706

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

    USGS Publications Warehouse

    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

  3. Analysis of metals in blue crabs, Callinectes sapidus, from two Connecticut estuaries

    SciTech Connect

    Jop, K.M.; Biever, R.C.; Hoberg, J.R.; Shepherd, S.P.

    1997-02-01

    Decisions involving the use and allocation of resources in the nation`s coastal and estuarine regions require reliable and continuous information about the status and trends of environmental quality in those areas. In recent years much attention has been focused on assessing environmental risks resulting from the manufacture, distribution, use and disposal of chemicals. Legislation and public concern have produced numerous regulations concerning the introduction of chemicals into surface waters which increase the potential for human exposure. There is considerable concern about the human health aspects of metal cycling especially in coastal and inland waters that are in proximity to large populations or industrial centers. Many of these compounds tend to remain in the ecosystem and eventually move from lower to higher trophic levels within the human food chain. Blue crabs, Callinectes sapidus Rathbun, are important members of the estuarine food chain due to high abundance and their multiple role as scavengers, predators and prey. Because of their omnivorous feeding characteristics and association with sediments, blue crabs are exposed and may potentially accumulate significant amount of pollutants above background seawater concentrations. This species represents one of the most valuable fishery resources in the southern states. According to Marcus and Mathews blue crabs ranked fifth in 1984 and fourth in 1985 behind shrimp, swordfish, oysters and hard clams in economic value, but first in total weight for both years in South Carolina. Although in Connecticut blue crabs are harvested mostly for personal consumption, their commercial value in other states makes the results from any environmental survey of great interest from the consideration of risk to human health. This study evaluated the level of contaminants in Blue crabs in the summer months by examining the concentration of selected metals in samples of muscle and hepatopancreas tissue. 12 refs., 3 tabs.

  4. Modeling the impacts of the European green crab on commercial shellfisheries.

    PubMed

    Grosholz, Edwin; Lovell, Sabrina; Besedin, Elena; Katz, Marilyn

    2011-04-01

    Coastal resource managers are often tasked with managing coastal ecosystems that are stressed by overexploitation, climate change, contaminants, and habitat loss, as well as biological invasions. Therefore, managers increasingly need better economic data to help them prioritize their management strategies and distribute their increasingly limited resources to those strategies. Despite frequent pronouncements about the substantial ecological and economic impacts of invasive species, there have been few if any rigorous analyses of the economic impacts of invasive species in coastal systems. Here we present a bioeconomic analysis of the impacts of the European green crab, Carcinus maenas, on commercial shellfisheries along the West Coast of the United States. Green crabs are among the most comprehensively studied and widely distributed invasive species in coastal systems, with established populations on every continent except Antarctica. Their impacts on commercial bivalve fisheries have been alleged or substantiated to varying degrees, but no formal analysis of the economic impacts of the green crab has been conducted. We assess economic impacts using a combination of ecological and economic models. The ecological models incorporate green crab dispersal and description of estuarine habitat and the relationship between green crab abundance and predation on prey populations. The economic analysis focuses on the green crab impacts on commercial shellfisheries, including both historical and present impacts of green crabs on several important shellfisheries, including soft-shell clams, blue mussels, scallops, hard-shell clams, and Manila clams. We conclude that the past and present economic impacts on the West Coast shellfisheries are minor, although losses could increase significantly if densities increase or with northward range expansion into Alaska.

  5. The role of epibenthic crustacean predators in an estuarine food web

    NASA Astrophysics Data System (ADS)

    Raffaelli, D.; Conacher, A.; McLachlan, H.; Emes, C.

    1989-02-01

    Two field experiments were carried out on an estuarine intertidal mudflat, enclosing varying densities of the crustacean predators Carcinus maenas and Crangon crangon. Effects of predation on prey densities were few and limited to cages with abnormally high densities of crabs. In both experiments there were significant effects on the size structure of the amphipod Corophium volutator. The results are compared with those from other caging experiments and it is suggested that, where marked, predation effects have been recorded unnaturally high densities of predators were used.

  6. Robust Soldier Crab Ball Gate

    NASA Astrophysics Data System (ADS)

    Gunji, Yukio-Pegio; Nishiyama, Yuta; Adamatzky, Andrew

    2011-09-01

    Based on the field observation of soldier crabs, we previously proposed a model for a swarm of soldier crabs. Here, we describe the interaction of coherent swarms in the simulation model, which is implemented in a logical gate. Because a swarm is generated by inherent perturbation, a swarm can be generated and maintained under highly perturbed conditions. Thus, the model reveals a robust logical gate rather than stable one. In addition, we show that the logical gate of swarms is also implemented by real soldier crabs (Mictyris guinotae).

  7. Novel Crab Cavity RF Design

    SciTech Connect

    Dudas, A.; Neubauer, M. L.; Sah, R.; Rimmer, B.; Wang, H.

    2011-03-01

    A 20-50 MV integrated transverse voltage is required for the Electron-Ion Collider. The most promising of the crab cavity designs that have been proposed in the last five years are the TEM type crab cavities because of the higher transverse impedance. The TEM design approach is extended here to a hybrid crab cavity that includes the input power coupler as an integral part of the design. A prototype was built with Phase I monies and tested at JLAB. The results reported on, and a system for achieving 20-50 MV is proposed.

  8. Movement patterns and trajectories of ovigerous blue crabs Callinectes sapidus during the spawning migration

    NASA Astrophysics Data System (ADS)

    Carr, Sarah D.; Tankersley, Richard A.; Hench, James L.; Forward, Richard B.; Luettich, Richard A.

    2004-08-01

    Female blue crabs ( Callinectes sapidus Rathbun) migrate from low salinity estuarine regions to high salinity regions near the ocean to release larvae. During this migration, ovigerous females use ebb-tide transport, a vertical migratory behavior in which they ascend into the water column during ebb tides, to move seaward to larval release areas. In order to determine the relationship of ebb-tide vertical migrations to local currents and the influence of these vertical migrations on the horizontal transport of blue crabs in the estuary, ovigerous females with mature embryos (˜1-3 days from hatching) were tracked near Beaufort Inlet, North Carolina (USA), in July and August 2001 and 2002. Crabs were tagged and tracked using ultrasonic telemetry, and currents near the crabs were measured simultaneously with a shipboard acoustic Doppler current profiler. During the two seasons, eight crabs were successfully tracked for periods ranging from 3.9-37.0 h and for distances ranging from 1.9-10.6 km. All crabs migrated seaward during the tracking periods. Crabs moved episodically during all tidal phases with periods of movement on the order of minutes to an hour. They moved with local currents in terms of both speed and direction during ebb tides, consistent with ebb-tide transport, and moved down-estuary (seaward) in opposition to local currents during flood tides. The percentage of time that crabs were active was higher during night ebb tides than during day ebb tides or flood tides and increased with increasing ebb-tide current speed. Mean migratory speeds were 0.11, 0.04, 0.08 and 0.02 m s -1 during night ebb, night flood, day ebb and day flood tides, respectively, and net migratory speeds were on the order of 5 km day -1. Due to the episodic nature of the crabs' movements, the total distances that crabs traveled during ebb tides ranged from 10-40% of the distances that passive particles could have traveled under the same conditions.

  9. Secondary production of the fiddler crab Uca rapax from mangrove areas under anthropogenic eutrophication in the Western Atlantic, Brazil.

    PubMed

    Costa, Tarso de M M; Soares-Gomes, Abilio

    2015-12-30

    Fiddler crabs Uca rapax were analyzed in three mangrove areas located in both a lagoon and estuarine system in order to study the influence of eutrophication on their population dynamics and production. Populations at the three sites showed a biased sex ratio. Densities were similar at the three sites, but biomass was higher at the lagoon system. Despite biomass being higher at the most eutrophic site, this site exhibited the lowest production. Regarding age structure, the population inhabiting the less eutrophic site mainly comprised younger crabs. The lower production and smaller P/B ratio found in the more eutrophic site were most likely consequences of a high mortality rate and an aged population. Our study evidences the high plasticity of the fiddler crab U. rapax, and confirms secondary production and P/B ratio estimates as useful tools to assess the effects of environmental change.

  10. The Great Crab Nebula Superflare

    NASA Video Gallery

    There are strange goings-on in the Crab Nebula. On April 12, 2011, NASA's Fermi Gamma-ray Space Telescope detected the most powerful in a series of gamma-ray flares occurring somewhere within the s...

  11. Antarctic crabs: invasion or endurance?

    PubMed

    Griffiths, Huw J; Whittle, Rowan J; Roberts, Stephen J; Belchier, Mark; Linse, Katrin

    2013-01-01

    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 "invasion hypothesis".

  12. Antarctic Crabs: Invasion or Endurance?

    PubMed Central

    Griffiths, Huw J.; Whittle, Rowan J.; Roberts, Stephen J.; Belchier, Mark; Linse, Katrin

    2013-01-01

    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

  13. Estuarine Ecology as Project Work.

    ERIC Educational Resources Information Center

    Humphreys, T. J.

    1981-01-01

    Discusses advantages of using an estuarine environment as a study area for A-level students and reviews organizational considerations. Details and references regarding a variety of suitable techniques are provided along with examples of results obtained by students at Waltham Forest College. (Author/DC)

  14. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Mid-Atlantic): Blue crab

    SciTech Connect

    Hill, J.; Fowler, D.L.; Van Den Avyle, M.J.

    1989-03-01

    Species profiles are summaries of the literature on taxonomy, life history, and environmental requirements of coastal fishes and aquatic invertebrates. They are prepared to assist with impact assessment. The blue crab, Callinectes sapidus, occurs in lower reaches of freshwater rivers, estuaries, and coastal waters along the Atlantic seaboard and Gulf of Mexico, and the species supports the largest crab fishery in the United States. Chesapeake Bay provides the greatest production of blue crabs on the east coast. The blue crab's high abundance in estuaries, diverse feeding habits, and importance as prey for other marine animals indicate its important role in the structure and function of estuarine communities. Female blue crabs spawn in high-salinity lower estuaries of coastal areas; the resulting larvae are planktonic and develop into juveniles at 5 to 10 weeks of age. Juveniles gradually migrate into shallower, less-saline upper estuaries and rivers where they grow and mature at 1-2 yr of age. Mating occurs in the upper estuaries after which females migrate to areas having higher salinities. Growth and survival of blue crabs are strongly affected by water temperature and salinity, but tolerances vary with life stage. Larvae require temperatures of 20-30/degree/C and salinities of 10-30 ppt for proper development, but salinity and temperature tolerances are broad for advanced juveniles and adults. Blue crabs use nearly all areas within estuaries as nursery habitat, and crab populations are sensitive to changes in physical features of contamination of these areas. 94 refs., 4 figs., 2 tabs.

  15. 40 CFR 408.60 - Applicability; description of the non-remote Alaskan whole crab and crab section processing...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-remote Alaskan whole crab and crab section processing subcategory. 408.60 Section 408.60 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.60 Applicability; description of the non-remote Alaskan whole crab and crab...

  16. 40 CFR 408.70 - Applicability; description of the remote Alaskan whole crab and crab section processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... remote Alaskan whole crab and crab section processing subcategory. 408.70 Section 408.70 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.70 Applicability; description of the remote Alaskan whole crab and crab section...

  17. 40 CFR 408.70 - Applicability; description of the remote Alaskan whole crab and crab section processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... remote Alaskan whole crab and crab section processing subcategory. 408.70 Section 408.70 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.70 Applicability; description of the remote Alaskan whole crab and crab section...

  18. 40 CFR 408.70 - Applicability; description of the remote Alaskan whole crab and crab section processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... remote Alaskan whole crab and crab section processing subcategory. 408.70 Section 408.70 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.70 Applicability; description of the remote Alaskan whole crab and crab section...

  19. 40 CFR 408.60 - Applicability; description of the non-remote Alaskan whole crab and crab section processing...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-remote Alaskan whole crab and crab section processing subcategory. 408.60 Section 408.60 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.60 Applicability; description of the non-remote Alaskan whole crab and crab...

  20. 40 CFR 408.60 - Applicability; description of the non-remote Alaskan whole crab and crab section processing...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-remote Alaskan whole crab and crab section processing subcategory. 408.60 Section 408.60 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.60 Applicability; description of the non-remote Alaskan whole crab and crab...

  1. 40 CFR 408.70 - Applicability; description of the remote Alaskan whole crab and crab section processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... remote Alaskan whole crab and crab section processing subcategory. 408.70 Section 408.70 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.70 Applicability; description of the remote Alaskan whole crab and crab section...

  2. 40 CFR 408.60 - Applicability; description of the non-remote Alaskan whole crab and crab section processing...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-remote Alaskan whole crab and crab section processing subcategory. 408.60 Section 408.60 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.60 Applicability; description of the non-remote Alaskan whole crab and crab...

  3. 40 CFR 408.70 - Applicability; description of the remote Alaskan whole crab and crab section processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... remote Alaskan whole crab and crab section processing subcategory. 408.70 Section 408.70 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.70 Applicability; description of the remote Alaskan whole crab and crab section...

  4. 40 CFR 408.60 - Applicability; description of the non-remote Alaskan whole crab and crab section processing...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-remote Alaskan whole crab and crab section processing subcategory. 408.60 Section 408.60 Protection of... SEAFOOD PROCESSING POINT SOURCE CATEGORY Non-Remote Alaskan Whole Crab and Crab Section Processing Subcategory § 408.60 Applicability; description of the non-remote Alaskan whole crab and crab...

  5. Diet variation of a generalist fish predator, grey snapper Lutjanus griseus, across an estuarine gradient: trade-offs of quantity for quality?

    PubMed

    Yeager, L A; Layman, C A; Hammerschlag-Peyer, C M

    2014-08-01

    This study examined diet, prey quality and growth for a generalist fish predator, grey snapper Lutjanus griseus, at five sites across an estuarine gradient in the Loxahatchee River estuary, Florida, U.S.A. Lutjanus griseus diets shifted from dominance by low quality, intertidal crabs upstream to an increased reliance on higher quality shrimp, fishes and benthic crabs downstream. Frequency of L. griseus with empty stomachs was higher at downstream sites. Lutjanus griseus growth rates did not vary among sites. Results indicate that L. griseus may be able to compensate for lower quality prey upstream by consuming more, and thus individuals are able to maintain similar levels of energy balance and growth rates across the estuarine gradient. Elucidating mechanisms, such as compensatory feeding, that enable generalist species to remain successful across habitat conditions are critical to understanding their organismal ecology and may facilitate predictions about the response of generalists to landscape alteration.

  6. Larval transport and its association with recruitment of blue crabs to Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Johnson, Donald R.; Hester, Betty S.

    1989-05-01

    The blue crab ( Calinectes sapidus) harvest in Chesapeake Bay has undergone large yearly fluctuations, creating hardships in the fishing industry and uncertainties in its management. It has previously been suggested that part of the fluctuation may be due to environmental influences during a sensitive period in their life history when blue crab larvae are planktonic outside the bay. During this period, they reside principally in the neuston where wind forced transport has the maximum influence. It is shown, through vector/scalar correlations of wind stress with harvest, that approximately 36% of the harvest variation can be accounted for by the wind patterns during the months from June through September. The influence of alongshore sea level slope and cummulative estuarine discharge (both relating to transport through pressure gradient forcing) on harvest were investigated, but the results were negligible, or ambiguous at best.

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

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on: (1... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Initial Issuance of Crab QS by Crab...

  8. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on: (1... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Initial Issuance of Crab QS by Crab...

  9. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on:(1... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Initial Issuance of Crab QS by Crab...

  10. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on:(1... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Initial Issuance of Crab QS by Crab...

  11. 50 CFR Table 7 to Part 680 - Initial Issuance of Crab QS by Crab QS Fishery

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... fisheries. 4 years 5. Pribilof red king and blue king crab (PIK) 4 years of the 5-year period beginning on... requirement. 4 years 6. St. Matthew blue king crab (SMB) 4 years of the 5-year period beginning on: (1... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Initial Issuance of Crab QS by Crab...

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

    PubMed Central

    Kersanach, Ralf; Cortinhas, Maria Cristina Silva; Prata, Pedro Fernandes Sanmartin; Dumont, Luiz Felipe Cestari; Proietti, Maíra Carneiro; Maggioni, Rodrigo; D’Incao, Fernando

    2016-01-01

    Population connectivity in the blue crab Callinectes sapidus was evaluated along 740 km of the Western South Atlantic coast. Blue crabs are the most exploited portunid in Brazil. Despite their economic importance, few studies report their ecology or population structure. Here we sampled four estuarine areas in southern Brazil during winter 2013 and summer 2014 in order to evaluate diversity, gene flow and structure of these populations. Nine microsatellite markers were evaluated for 213 adult crabs, with identification of seven polymorphic loci and 183 alleles. Pairwise FST values indicated low population structure ranging from -0.00023 to 0.01755. A Mantel test revealed that the geographic distance does not influence genetic (r = -0.48), and structure/migration rates confirmed this, showing that even the populations located at the opposite extremities of our covered region presented low FST and exchanged migrants. These findings show that there is a significant amount of gene flow between blue crab populations in South Brazil, likely influenced by local current dynamics that allow the transport of a high number of larvae between estuaries. Considering the elevated gene flow, the populations can be considered a single genetic stock. However, further information on population size and dynamics, as well as fishery demands and impacts at different regions, are necessary for harvest management purposes. PMID:27064977

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

    PubMed

    Lacerda, Ana Luzia Figueiredo; Kersanach, Ralf; Cortinhas, Maria Cristina Silva; Prata, Pedro Fernandes Sanmartin; Dumont, Luiz Felipe Cestari; Proietti, Maíra Carneiro; Maggioni, Rodrigo; D'Incao, Fernando

    2016-01-01

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

  14. Biomarkers in mangrove root crab Goniopsis cruentata for evaluating quality of tropical estuaries.

    PubMed

    Davanso, Marcela Bergo; Moreira, Lucas Buruaem; Pimentel, Marcionília Fernandes; Costa-Lotufo, Letícia Veras; de Souza Abessa, Denis Moledo

    2013-10-01

    The present study reports the use of biomarkers analyzes in mangrove root crab Goniopsis cruentata tissues to assess the environmental quality of two tropical estuarine areas. Animals from Ceará River estuary presented inhibition of ChE and GST enzymatic activities and higher rates of DNA damage with respect to those sampled in a pristine environment. G. cruentata appears to represent a proper species to monitor the quality of tropical estuaries. Since Ceará River is a legally protected area, this survey highlight the needs to implement actions to control pollution loads and improve the protection of natural ecosystems and resources.

  15. Distortion of Crabbed Bunch Due to Electron Cloud and Global Crabbing

    SciTech Connect

    Wang, L.; Raubenheimer, T.O.; Cai, Y.; /SLAC

    2008-08-01

    Crab cavities may be used improve the luminosity in colliding beam colliders with crab crossing. In a global crab crossing correction, only one crab cavity is installed in each ring and the crab cavities generate a horizontally titled bunch oscillating around the ring. The electron cloud in positively charged rings may distort the crabbed bunch and cause the luminosity drop. This paper briefly estimates the distortion of positron bunch due to the electron cloud with global crab and estimates the effect in the KEKB and possible LHC upgrades.

  16. Effect of copper and cadmium on three Malaysian tropical estuarine invertebrate larvae.

    PubMed

    Ramachandran, S; Patel, T R; Colbo, M H

    1997-03-01

    Three species of tropical estuarine invertebrates were exposed to copper sulfate and cadmium chloride to investigate their potential as test specimens for sediment toxicity assays in the South-east Asian regions. The larvae of the reef sea urchin (Diadema setosum), the oyster (Crassostrea iradalei), and the mud crab (Scylla seratta Forskall) were used in the 48-hr assays with copper and cadmium as reference toxicants. In addition the sea urchin were tested for end point measurements at different stages of the larval development and a 60-min sperm bioassay. The study revealed that the sea urchin first cleavage, which is an assay end point and which takes place about 1 hr after fertilization, was the most sensitive stage for both toxicants, with copper being more toxic than cadmium. Sensitivity comparisons between the three invertebrate larvae revealed the mud crab zoea larvae to be most sensitive for cadmium with an LC50 value of 0.078 microgram/ml, while the sea urchin was more sensitive for copper, with EC50 values of 0.01 microgram/ml at the first cleavage stage and 0.04 microgram/ml at the pluteus larva stage. All the invertebrates tested gave responses that made them suitable test organisms for metal bioassays in the tropical estuarine environment.

  17. Mercury, lead, and cadmium in blue crabs, Callinectes sapidus, from the Atlantic coast of Florida, USA: a multipredator approach.

    PubMed

    Adams, Douglas H; Engel, Marc E

    2014-04-01

    Blue crabs, Callinectes sapidus, from the Atlantic coast of Florida were analyzed for total mercury, methylmercury, lead, and cadmium. Paired samples of two tissue types were analyzed for each crab, (1) muscle tissue (cheliped and body muscles) and (2) whole-body tissue (all organs, muscle tissue and connective tissue), for evaluation of the concentration of metals available to human consumers as well as estuarine predators. There were clear patterns of tissue-specific partitioning for each metal. Total mercury was significantly greater in muscle tissue (mean=0.078 µg/g) than in whole-body tissue (mean=0.055 µg/g). Conversely, whole-body concentrations of lead and cadmium (means=0.131 and 0.079 µg/g, respectively) were significantly greater than concentrations in muscle (means=0.02 and 0.029 µg/g, respectively). There were no significant correlations between any metal contaminant and crab size. Cadmium levels were significantly greater in the muscle tissue of females, but, no other sex-related differences were seen for other metals or tissue types. Methylmercury composed 93-100% of the total mercury in tissues. Compared to previous blue crab studies from different regions of the United States, mean concentrations of mercury, lead, and cadmium were relatively low, although isolated groups or individual blue crabs accumulated high metal concentrations.

  18. Monitoring The Crab Pulsar

    NASA Technical Reports Server (NTRS)

    Rots, Arnold H.; Swank, Jean (Technical Monitor)

    2001-01-01

    The monitoring of the X-ray pulses from the Crab pulsar is still ongoing at the time of this writing, and we hope to be able to continue the campaign for the life of the XTE mission. We have established beyond all doubt that: (1) the X-ray main pulse leads the radio pulse by approximately 300 microseconds, (2) this phase lag is constant and not influenced by glitches, (3) this lag does not depend on X-ray energy, (4) the relative phase of the two X-ray pulses does not vary, and (5) the spectral indices of primary, secondary, and inter-pulse are distinct and constant. At this time we are investigating whether the radio timing ephemeris can be replaced by an x-ray ephemeris and whether any long-time timing ephemeris can be established. If so, it would enable use to study variations in pulse arrival times at a longer time scales. Such a study is easier in x-rays than at radio wavelengths since the dispersion measure plays no role. These results were reported at the 2000 HEAD Meeting in Honolulu, HI. Travel was paid partly out of this grant. The remainder was applied toward the acquisition of a laptop computer that allows independent and fast analysis of all monitoring observations.

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

    PubMed

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

    2016-12-06

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

  20. Are Crab nanoshots Schwinger sparks?

    SciTech Connect

    Stebbins, Albert; Yoo, Hojin

    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.

  1. LHC crab-cavity aspects and strategy

    SciTech Connect

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

    2010-05-23

    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.

  2. Environmental predictors of estuarine fish landings along a temperate coastline

    NASA Astrophysics Data System (ADS)

    Saintilan, Neil; Wen, Li

    2012-11-01

    The regulation of freshwater flow into estuaries has been identified as a potential threat to estuarine ecosystem structure and function, and the productivity of fisheries in particular. Correlative studies are one means by which associations between freshwater inputs and commercial landings have been identified. The study compared monthly landings of five species of finfish and two species of crustacean with monthly and 6-month running means of river discharge, climatic variables (temperature and rainfall) and the area of vegetated habitat (saltmarsh, mangrove and seagrass) for 11 temperate estuaries on the NSW coast. The monthly climatic and discharge record covered a 10-year period (1997-2007). High river discharge and rainfall were associated with higher catches of flathead (Platycephalus spp.) and Mullet (Mugil spp.), a result consistent with subtropical estuaries to the north. We found no relationships between landings and river discharge for any of the other species, which included school prawns (Metapenaeus macleayi). Temporal variability at a monthly time-step was more consistently associated with variation in temperature, reflecting seasonal variation in activity, and possibly fishing effort. Landings of several species showed strong habitat relationships, with greater seagrass area consistently associated with higher catches of blue swimmer crab (Portunis pelagicus), and intertidal wetlands (mangrove and saltmarsh) with mud crab (Scylla serrata), school prawns, flathead, and mullet (Mugil spp.), a result consistent with habitat-scale surveys. The results draw into question the efficacy of dam releases as stimulants of fisheries productivity in the region, although the effects of flow on juvenile populations and catadromous species were not studied.

  3. Uptake and loss of dissolved 109Cd and 75Se in estuarine macroinvertebrates.

    PubMed

    Alquezar, Ralph; Markich, Scott J; Twining, John R

    2007-04-01

    Semaphore crabs (Heloecius cordiformis), soldier crabs (Mictyris platycheles), ghost shrimps (Trypaea australiensis), pygmy mussels (Xenostrobus securis), and polychaetes (Eunice sp.), key benthic prey items of predatory fish commonly found in estuaries throughout southeastern Australia, were exposed to dissolved (109)Cd and (75)Se for 385 h at 30 k Bq/l (uptake phase), followed by exposure to radionuclide-free water for 189 h (loss phase). The whole body uptake rates of (75)Se by pygmy mussels, semaphore crabs and soldier crabs were 1.9, 2.4 and 4.1 times higher than (109)Cd, respectively. There were no significant (P>0.05) differences between the uptake rates of (75)Se and (109)Cd for ghost shrimps and polychaetes. The uptake rates of (109)Cd and (75)Se were highest in pygmy mussels; about six times higher than in soldier crabs for (109)Cd and in polychaetes for (75)Se - the organisms with the lowest uptake rates. The loss rates of (109)Cd and (75)Se were highest in semaphore crabs; about four times higher than in polychaetes for (109)Cd and nine times higher than in ghost shrimps for (75)Se - the organisms with the lowest loss rates. The loss of (109)Cd and (75)Se in all organisms was best described by a two (i.e. short and a longer-lived) compartment model. In the short-lived, or rapidly exchanging, compartment, the biological half-lives of (75)Se (16-39 h) were about three times greater than those of (109)Cd (5-12h). In contrast, the biological half-lives of (109)Cd in the longer-lived, or slowly exchanging compartment(s), were typically greater (1370-5950 h) than those of (75)Se (161-1500 h). Semaphore crabs had the shortest biological half-lives of both radionuclides in the long-lived compartment, whereas polychaetes had the greatest biological half-life for (109)Cd (5950 h), and ghost shrimps had the greatest biological half-life for (75)Se (1500 h). This study provides the first reported data for the biological half-lives of Se in estuarine decapod

  4. Uptake, metabolism and sub-lethal effects of BDE-47 in two estuarine invertebrates with different trophic positions.

    PubMed

    Díaz-Jaramillo, M; Miglioranza, K S B; Gonzalez, M; Barón, E; Monserrat, J M; Eljarrat, E; Barceló, D

    2016-06-01

    Two microcosm types -sediment-biota and biota-biota- were constructed to simulate different pathways of BDE-47 uptake, metabolism and oxidative stress effects in two key estuarine invertebrates (polychaete Laeonereis acuta and crab Cyrtograpsus angulatus). In the sediment-biota experiment, both species were exposed to spiked sediments; an environmentally reported and a high concentration of BDE-47 for 2 weeks. In the biota-biota experiment, crabs were fed with polychaetes pre-exposed to BDE-47 in the sediment-biota experiment. The sediment-biota experiment first revealed that polychaetes significantly accumulated BDE-47 (biota-sediment accumulation factor >2; p < 0.05) to a much greater extent than the crab organs (muscle, hepatopancreas, gills) at both sediment concentrations. For oxidative stress responses, polychaete and crab tissues exposed to spiked sediment showed a significant increase (p < 0.05) of only glutathione S-transferase (GST) activity with respect to controls in both BDE-47 concentrations. No lipid peroxidation (TBARS) or total antioxidant capacity (ACAP) changes were evident in the species or organs exposed to either BDE-47 sediment concentration. The biota-biota experiment showed that feeding crabs with pre-exposed polychaetes caused BDE-47 accumulation in organs as well as significant amounts of BDE-47 eliminated through feces (p < 0.05). Unlike the sediment-biota exposure, crabs fed with pre-exposed BDE-47 polychaetes showed the most conspicuous oxidative stress responses. Significant changes in GST and ACAP in both hepatopancreas and gills, in addition to enhanced TBARS levels in the hepatopancreas with respect to controls (p < 0.05), revealed that BDE-47 assimilated by invertebrates represents a potential source of toxicity to their predators. No methoxylated metabolites (MeO-PBDEs) were detected during BDE-47 metabolism in the invertebrates in either of the two different exposure types. In contrast, hydroxylated metabolites (OH

  5. 50 CFR Table 6 to Part 680 - Crab Grade Codes

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Crab Grade Codes 6 Table 6 to Part 680..., Table 6 Table 6 to Part 680—Crab Grade Codes Grade/code Description 1 Standard or premium quality crab or crab sections. 2 Lower quality product, e.g., dirty shelled crab or a pack that is of...

  6. 50 CFR Table 6 to Part 680 - Crab Grade Codes

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Crab Grade Codes 6 Table 6 to Part 680..., Table 6 Table 6 to Part 680—Crab Grade Codes Grade/code Description 1 Standard or premium quality crab or crab sections. 2 Lower quality product, e.g., dirty shelled crab or a pack that is of...

  7. Sertraline accumulation and effects in the estuarine decapod Carcinus maenas: importance of the history of exposure to chemical stress.

    PubMed

    Rodrigues, Aurélie P; Santos, Lúcia H M L M; Ramalhosa, Maria João; Delerue-Matos, Cristina; Guimarães, Laura

    2015-01-01

    Sertraline is widely prescribed worldwide and frequently detected in aquatic systems. There is, however, a remarkable gap of information on its potential impact on estuarine and coastal invertebrates. This study investigated sertraline accumulation and effects in Carcinus maenas. Crabs from a moderately contaminated (Lima) and a low-impacted (Minho) estuary were exposed to environmental and high levels of sertraline (0.05, 5, 500 μg L(-1)). A battery of biomarkers related to sertraline mode of action was employed to assess neurotransmission, energy metabolism, biotransformation and oxidative stress pathways. After a seven-day exposure, sertraline accumulation in crabs' soft tissues was found in Lima (5 μg L(-1): 15.3 ng L(-1) ww; 500 μg L(-1): 1010 ng L(-1) ww) and Minho (500 μg L(-1): 605 ng L(-1) ww) animals. Lima crabs were also more sensitive to sertraline than those from Minho, exhibiting decreased acetylcholinesterase activity, indicative of ventilatory and locomotory dysfunction, inhibition of anti-oxidant enzymes and increased oxidative damage at ≥ 0.05 μg L(-1). The Integrated Biomarker Response (IBR) index indicated their low health status. In addition, Minho crabs showed non-monotonic responses of acetylcholinesterase suggestive of hormesis. The results pointed an influence of the exposure history on differential sensitivity to sertraline and the need to perform evaluations with site-specific ecological receptors to increase relevance of risk estimations when extrapolating from laboratory to field conditions.

  8. Simulation modeling of estuarine ecosystems

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.

    1980-01-01

    A simulation model has been developed of Galveston Bay, Texas ecosystem. Secondary productivity measured by harvestable species (such as shrimp and fish) is evaluated in terms of man-related and controllable factors, such as quantity and quality of inlet fresh-water and pollutants. This simulation model used information from an existing physical parameters model as well as pertinent biological measurements obtained by conventional sampling techniques. Predicted results from the model compared favorably with those from comparable investigations. In addition, this paper will discuss remotely sensed and conventional measurements in the framework of prospective models that may be used to study estuarine processes and ecosystem productivity.

  9. 50 CFR 622.247 - Landing golden crab intact.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ATLANTIC Golden Crab Fishery of the South Atlantic Region § 622.247 Landing golden crab intact. The... ashore. (a) A golden crab in or from the South Atlantic EEZ must be maintained in whole condition...

  10. 50 CFR 622.247 - Landing golden crab intact.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ATLANTIC Golden Crab Fishery of the South Atlantic Region § 622.247 Landing golden crab intact. The... ashore. (a) A golden crab in or from the South Atlantic EEZ must be maintained in whole condition...

  11. 15 CFR 921.51 - Estuarine research guidelines.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Estuarine research guidelines. 921.51... MANAGEMENT NATIONAL ESTUARINE RESEARCH RESERVE SYSTEM REGULATIONS Special Research Projects § 921.51 Estuarine research guidelines. (a) Research within the National Estuarine Research Reserve System shall...

  12. 15 CFR 921.51 - Estuarine research guidelines.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 3 2012-01-01 2012-01-01 false Estuarine research guidelines. 921.51... MANAGEMENT NATIONAL ESTUARINE RESEARCH RESERVE SYSTEM REGULATIONS Special Research Projects § 921.51 Estuarine research guidelines. (a) Research within the National Estuarine Research Reserve System shall...

  13. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Initial Issuance of Crab PQS by Crab...

  14. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Initial Issuance of Crab PQS by Crab...

  15. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Initial Issuance of Crab PQS by Crab...

  16. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Initial Issuance of Crab PQS by Crab...

  17. 50 CFR Table 9 to Part 680 - Initial Issuance of Crab PQS by Crab QS Fishery

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Islands red and blue king crab (PIK) 3 years of the 3-year period beginning on: (1) September 15-26, 1996; (2) September 15-29, 1997; and (3) September 15-28, 1998. St. Matthew blue king crab (SMB) 3 years of... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Initial Issuance of Crab PQS by Crab...

  18. Bacterial diseases of crabs: a review.

    PubMed

    Wang, W

    2011-01-01

    Bacterial diseases of crabs are manifested as bacteremias caused by organisms such as Vibrio, Aeromonas, and a Rhodobacteriales-like organism or tissue and organ tropic organisms such as chitinoclastic bacteria, Rickettsia intracellular organisms, Chlamydia-like organism, and Spiroplasma. This paper provides general information about bacterial diseases of both marine and freshwater crabs. Some bacteria pathogens such as Vibrio cholerae and Vibrio vulnificus occur commonly in blue crab haemolymph and should be paid much attention to because they may represent potential health hazards to human beings because they can cause serious diseases when the crab is consumed as raw sea food. With the development of aquaculture, new diseases associated with novel pathogens such as spiroplasmas and Rhodobacteriales-like organisms have appeared in commercially exploited crab species in recent years. Many potential approaches to control bacterial diseases of crab will be helpful and practicable in aquaculture.

  19. Hermit crabs, humans and crowded house markets.

    PubMed

    Barnes, David K A

    2002-12-01

    There is a complex and dynamic interrelationhip between hermit crabs, humans and the coastal environment. Hermit crab homes (shells) are often hard to come by, but humans are helping out by piling middens of shells and rubbish on beachers. Hermit crabs are useful to humans as fishing bait, pets and living wasted disposal systems, and so useful to other animals that they may even be hijacked.

  20. Final focus designs for crab waist colliders

    NASA Astrophysics Data System (ADS)

    Bogomyagkov, A.; Levichev, E.; Piminov, P.

    2016-12-01

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

  1. Does the Crab Have a Shell

    DTIC Science & Technology

    1995-12-01

    We present deep images of a region around the Crab Nebula made with the VLA, utilizing new imaging and deconvolution algorithms in a search for a...the observed nebula. No radio emission was detected from an extended source outside the Crab Nebula . Our limits on surface brightness are sufficiently...a steepening of the spectral index along the boundary of the Crab Nebula itself, the signature of an outer shock. However, contrary to previous

  2. OSSE Observations of the Crab Pulsar

    DTIC Science & Technology

    1994-01-01

    Crab nebula and pulsar (Leventhal, MacCallum, & Watts 1977; Ling et al. 1979; Strickman, Johnson, & Kurfess 1979; Ayre et al. 1983; Agrinier et al...emission from the Crab nebula , as well as detector background. The background portion was then subtracted from the entire light curve. The phase ranges we...detections c) References for previous upper limits d) Based on total Crab nebula plus pulsar spectrum e) Upper limits (3) f) Comments related to

  3. Downwelling wind, tides, and estuarine plume dynamics

    NASA Astrophysics Data System (ADS)

    Lai, Zhigang; Ma, Ronghua; Huang, Mingfen; Chen, Changsheng; Chen, Yong; Xie, Congbin; Beardsley, Robert C.

    2016-06-01

    The estuarine plume dynamics under a downwelling-favorable wind condition were examined in the windy dry season of the Pearl River Estuary (PRE) using the PRE primitive-equation Finite-Volume Community Ocean Model (FVCOM). The wind and tide-driven estuarine circulation had a significant influence on the plume dynamics on both local and remote scales. Specifically, the local effect of downwelling-favorable winds on the plume was similar to the theoretical descriptions of coastal plumes, narrowing the plume width, and setting up a vertically uniform downstream current at the plume edge. Tides tended to reduce these plume responses through local turbulent mixing and advection from upstream regions, resulting in an adjustment of the isohalines in the plume and a weakening of the vertically uniform downstream current. The remote effect of downwelling-favorable winds on the plume was due to the wind-induced estuarine sea surface height (SSH), which strengthened the estuarine circulation and enhanced the plume transport accordingly. Associated with these processes, tide-induced mixing tended to weaken the SSH gradient and thus the estuarine circulation over a remote influence scale. Overall, the typical features of downwelling-favorable wind-driven estuarine plumes revealed in this study enhanced our understanding of the estuarine plume dynamics under downwelling-favorable wind conditions.

  4. Population biology of the portunid crab Callinectes arcuatus Ordway in the Gulf of Nicoya, Costa Rica, Central America

    NASA Astrophysics Data System (ADS)

    Dittel, Ana I.; Epifanio, C. E.; Chavarria, Juan Bautista

    1985-05-01

    Tropical blue crabs Callinectes arcuatus were collected by trawling in the Gulf of Nicoya on the Pacific coast of Costa Rica, Central America. The gulf population was generally dominated by females. Adult females were common in the upper, more estuarine regions of the gulf during rainy season, but appeared to migrate to the lower gulf during dry season for spawning. Biomass varied with seasonal changes in abundance, but was generally similar to biomass of C. sapidus in Chesapeake Bay. Analysis of size frequency indicated that the population is numerically dominated by adults during January and February and that juveniles are common during the remainder of the year. Extrapolation of available data suggests that female crabs reach maturity in approximately one year after hatching.

  5. The Crab pulsar at VHE

    NASA Astrophysics Data System (ADS)

    Zanin, Roberta

    2017-03-01

    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.

  6. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Gulf of Mexico): Blue crab. [Callinectes sapidus

    SciTech Connect

    Perry, H.M.; McIlwain, T.D.

    1986-06-01

    The blue crab, Callinectes sapidus, is common in tidal marsh estuaries and coastal waters of the Gulf of Mexico, occupying a variety of habitats depending upon the physiological requirements of each particular stage in its life history. Spawning occurs from spring through fall in high salinity estuarine and/or coastal waters. Development through the 7 zoeal stages requires approximately 31 days and occurs offshore. The megalopal stage is usually completed within a week. Recruitment to the estuary occurs during the megalopal stage. Molt to the first crab takes place within the estuary. Juveniles exhibit wide seasonal and areal distribution. Growth is rapid and blue crabs in the Gulf of Mexico may reach maturity within a year. Factors affecting growth and survival include food availability, predation, substratum, available habitat, temperature, salinity and pollutants. Blue crabs do not conform to specific trophic levels and are characterized as opportunistic benthic omnivores. Their diverse feeding habits and their importance as prey species for a variety of organisms make them an integral part of coastal ecosystems.

  7. Ecohydraulics and Estuarine Wetland Rehabilitation

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. F.; Howe, A.; Saintilan, N.; Spencer, J.

    2004-12-01

    The hydraulics or water flow in wetlands is known to be a key factor influencing ecosystem development in estuarine wetland environments. The relationship is indirect, with the hydraulics of wetlands influencing a host of factors including soil salinity, waterlogging, sediment transport, sediment chemistry, vegetation dispersal and growth and nutrient availability and cycling. The relationship is also not one way, with the hydraulics of wetlands being influenced by plant and animal activity. Understanding these complex interactions is fundamental for the adequate management of estuarine wetlands. Listed as a Wetland of International Importance under the 1971 Ramsar Convention, the Hunter River estuary is regarded as the most significant site for migratory shorebirds in New South Wales, Australia. Over the past 20 years, the number of migratory shorebirds in the estuary has sharply declined from 8,000 to 4,000 approx. Alteration of bird habitat is believed to be one of the reasons for this alarming trend. In 2004 we started a three-year program to investigate the links between hydraulics, sediment, benthic invertebrates, vegetation and migratory shorebird habitat in the estuary. During the first year we have focused on a highly disturbed part of the Hunter estuary wetlands located on Ash Island. The area is one of the major roosting sites in the estuary and is characterized by a complex hydraulic regime due to a restricted tidal interchange with the Hunter River and the presence of infrastructure for the maintenance of power lines (i.e., roads, bridges, culverts). Salt marshes, mudflat and mangroves are the dominant vegetation types. The monitoring program includes measurements of water levels, salinity, discharge, velocity, turbulence, sediment transport and deposition, plant species and density, soil composition and benthic invertebrates coordinated with observations of bird habitat utilization on a number of locations throughout the wetland and for different flow

  8. CHANGES IN THE CRAB PULSAR

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Scientists are learning more about how pulsars work by studying a series of Hubble Space Telescope images of the heart of the Crab Nebula. The images, taken over a period of several months, show that the Crab is a far more dynamic object than previously understood. At the center of the nebula lies the Crab Pulsar. The pulsar is a tiny object by astronomical standards -- only about six miles across -- but has a mass greater than that of the Sun and rotates at a rate of 30 times a second. As the pulsar spins its intense magnetic field whips around, acting like a sling shot, accelerating subatomic particles and sending them hurtling them into space at close to the speed of light. The tiny pulsar and its wind are the powerhouse for the entire Crab Nebula, which is 10 light-years across -- a feat comparable to an object the size of a hydrogen atom illuminating a volume of space a kilometer across. The three pictures shown here, taken from the series of Hubble images, show dramatic changes in the appearance of the central regions of the nebula. These include wisp-like structures that move outward away from the pulsar at half the speed of light, as well as a mysterious 'halo' which remains stationary, but grows brighter then fainter over time. Also seen are the effects of two polar jets that move out along the rotation axis of the pulsar. The most dynamic feature seen -- a small knot that 'dances around' so much that astronomers have been calling it a 'sprite' -- is actually a shock front (where fast-moving material runs into slower-moving material)in one of these polar jets. The telescope captured the images with the Wide Field and Planetary Camera 2 using a filter that passes light of wavelength around 550 nanometers, near the middle of the visible part of the spectrum. The Crab Nebula is located 7,000 light-years away in the constellation Taurus. Credit: Jeff Hester and Paul Scowen (Arizona State University), and NASA

  9. Novel Geometries for the LHC Crab Cavity

    SciTech Connect

    Hall, B.; Burt, G.; Smith, J. D.A.; Rimmer, R.; Wang, H.; Delayen, J.; Calaga, R.

    2009-05-01

    In 2017 the LHC is envisioned to increase its luminosity via an upgrade. This upgrade is likely to require a large crossing angle hence a crab cavity is required to align the bunches prior to collision. There are two possible schemes for crab cavity implementation, global and local. In a global crab cavity the crab cavity is far from the IP and the bunch rotates back and forward as it traverses around the accelerator in a closed orbit. For this scheme a two-cell elliptical squashed cavity at 800 MHz is preferred. To avoid any potential beam instabilities all the parasitic modes of the cavities must be damped strongly, however crab cavities have lower order and same order modes in addition to the usual higher order modes and hence a novel damping scheme must be used to provide sufficient damping of these modes. In the local scheme two crab cavities are placed at each side of the IP two start and stop rotation of the bunches. This would require crab cavities much smaller transversely than in the global scheme but the frequency cannot be increased any higher due to the long bunch length of the LHC beam. This will require a novel compact crab cavity design. A superconducting version of a two rod coaxial deflecting cavity as a suitable design is proposed in this paper.

  10. Particle beam and crabbing and deflecting structure

    DOEpatents

    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.

  11. HUBBLE CAPTURES DYNAMICS OF CRAB NEBULA (color)

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A new sequence of Hubble Space Telescope images of the remnant of a tremendous stellar explosion is giving astronomers a remarkable look at the dynamic relationship between the tiny Crab Pulsar and the vast nebula that it powers. This colorful photo shows a ground-based image of the entire Crab Nebula, the remnant of a supernova explosion witnessed over 900 years ago. The nebula, which is 10 light-years across, is located 7,000 light-years away in the constellation Taurus. The green, yellow and red filaments concentrated toward the edges of the nebula are remnants of the star that were ejected into space by the explosion. At the center of the Crab Nebula lies the Crab Pulsar -- the collapsed core of the exploded star. The Crab Pulsar is a rapidly rotating neutron star -- an object only about six miles across, but containing more mass than our Sun. As it rotates at a rate of 30 times per second the Crab Pulsar's powerful magnetic field sweeps around, accelerating particles, and whipping them out into the nebula at speeds close to that of light. The blue glow in the inner part of the nebula -- light emitted by energetic electrons as they spiral through the Crab's magnetic field -- is powered by the Crab Pulsar. Credit: Jeff Hester and Paul Scowen (Arizona State University), and NASA

  12. The sediment and hydrographic characteristics of three horseshoe crab nursery beaches in hong kong

    NASA Astrophysics Data System (ADS)

    Chiu, Helen M. C.; Morton, Brian

    2003-04-01

    Horseshoe crab juveniles have been recorded from sand and sandy-mud nursery beaches at Pak Nai (western New Territories), San Tau and Shui Hau (Lantau Island), Hong Kong. In order to provide a better understanding of these beaches and to identify those plausible factors which have made them preferred by spawning horseshoe crabs, environmental parameters, including temperature, salinity, pH and dissolved oxygen content of the water, and particle size distribution and organic matter content of the sediments at the three sites, were determined and compared. The hydrographic, and sediment data obtained for the three study sites have revealed some common environmental features. The three nursery beaches are relatively remote, and far (in Hong Kong terms) from urbanized and densely populated areas. The beaches are generally well sheltered from strong wave action and inundated regularly by estuarine waters. Horseshoe crab adults tend to select these beaches for spawning as their protected features ensures the laid eggs are less likely to be washed out of the sand, and hatched juveniles can feed on the meiofauna and grow. Sediments of the three beaches largely comprise medium-sized sand particles and are moderately sorted, suggesting medium porosity and good water permeability. Such a sand type, with the generally high oxygen levels in incursing waters, may help create a well-oxygenated micro-environment for the normal development of horseshoe crab eggs, larvae and juveniles. Lantau Island beaches at San Tau and Shui Hau are relatively free from organic pollution, as reflected in generally high dissolved oxygen level, and low BOD5 and ammonia nitrogen values. Pak Nai is, however, more polluted.

  13. Most Detailed Image of the Crab Nebula

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This new Hubble image -- one among the largest ever produced with the Earth-orbiting observatory -- shows the most detailed view so far of the entire Crab Nebula ever made. The Crab is arguably the single most interesting object, as well as one of the most studied, in all of astronomy. The image is the largest image ever taken with Hubble's WFPC2 workhorse camera.

    The Crab Nebula is one of the most intricately structured and highly dynamical objects ever observed. The new Hubble image of the Crab was assembled from 24 individual exposures taken with the NASA/ESA Hubble Space Telescope and is the highest resolution image of the entire Crab Nebula ever made.

  14. What brakes the Crab pulsar?

    NASA Astrophysics Data System (ADS)

    Čadež, A.; Zampieri, L.; Barbieri, C.; Calvani, M.; Naletto, G.; Barbieri, M.; Ponikvar, D.

    2016-03-01

    Context. Optical observations provide convincing evidence that the optical phase of the Crab pulsar follows the radio one closely. Since optical data do not depend on dispersion measure variations, they provide a robust and independent confirmation of the radio timing solution. Aims: The aim of this paper is to find a global mathematical description of Crab pulsar's phase as a function of time for the complete set of published Jodrell Bank radio ephemerides (JBE) in the period 1988-2014. Methods: We apply the mathematical techniques developed for analyzing optical observations to the analysis of JBE. We break the whole period into a series of episodes and express the phase of the pulsar in each episode as the sum of two analytical functions. The first function is the best-fitting local braking index law, and the second function represents small residuals from this law with an amplitude of only a few turns, which rapidly relaxes to the local braking index law. Results: From our analysis, we demonstrate that the power law index undergoes "instantaneous" changes at the time of observed jumps in rotational frequency (glitches). We find that the phase evolution of the Crab pulsar is dominated by a series of constant braking law episodes, with the braking index changing abruptly after each episode in the range of values between 2.1 and 2.6. Deviations from such a regular phase description behave as oscillations triggered by glitches and amount to fewer than 40 turns during the above period, in which the pulsar has made more than 2 × 1010 turns. Conclusions: Our analysis does not favor the explanation that glitches are connected to phenomena occurring in the interior of the pulsar. On the contrary, timing irregularities and changes in slow down rate seem to point to electromagnetic interaction of the pulsar with the surrounding environment.

  15. Thermal biology of the sub-polar-temperate estuarine crab Hemigrapsus crenulatus (Crustacea: Decapoda: Varunidae).

    PubMed

    Cumillaf, Juan P; Blanc, Johnny; Paschke, Kurt; Gebauer, Paulina; Díaz, Fernando; Re, Denisse; Chimal, María E; Vásquez, Jorge; Rosas, Carlos

    2016-02-15

    Optimum temperatures can be measured through aerobic scope, preferred temperatures or growth. A complete thermal window, including optimum, transition (Pejus) and critical temperatures (CT), can be described if preferred temperatures and CT are defined. The crustacean Hemigrapsus crenulatus was used as a model species to evaluate the effect of acclimation temperature on: (i) thermal preference and width of thermal window, (ii) respiratory metabolism, and (iii) haemolymph proteins. Dependant on acclimation temperature, preferred temperature was between 11.8°C and 25.2°C while CT was found between a minimum of 2.7°C (CTmin) and a maximum of 35.9°C (CTmax). These data and data from tropical and temperate crustaceans were compared to examine the association between environmental temperature and thermal tolerance. Temperate species have a CTmax limit around 35°C that corresponded with the low CTmax limit of tropical species (34-36°C). Tropical species showed a CTmin limit around 9°C similar to the maximum CTmin of temperate species (5-6°C). The maximum CTmin of deep sea species that occur in cold environments (2.5°C) matched the low CTmin values (3.2°C) of temperate species. Results also indicate that the energy required to activate the enzyme complex (Ei) involved in respiratory metabolism of ectotherms changes along the latitudinal gradient of temperature.

  16. Thermal biology of the sub-polar–temperate estuarine crab Hemigrapsus crenulatus (Crustacea: Decapoda: Varunidae)

    PubMed Central

    Cumillaf, Juan P.; Blanc, Johnny; Paschke, Kurt; Gebauer, Paulina; Díaz, Fernando; Re, Denisse; Chimal, María E.; Vásquez, Jorge; Rosas, Carlos

    2016-01-01

    ABSTRACT Optimum temperatures can be measured through aerobic scope, preferred temperatures or growth. A complete thermal window, including optimum, transition (Pejus) and critical temperatures (CT), can be described if preferred temperatures and CT are defined. The crustacean Hemigrapsus crenulatus was used as a model species to evaluate the effect of acclimation temperature on: (i) thermal preference and width of thermal window, (ii) respiratory metabolism, and (iii) haemolymph proteins. Dependant on acclimation temperature, preferred temperature was between 11.8°C and 25.2°C while CT was found between a minimum of 2.7°C (CTmin) and a maximum of 35.9°C (CTmax). These data and data from tropical and temperate crustaceans were compared to examine the association between environmental temperature and thermal tolerance. Temperate species have a CTmax limit around 35°C that corresponded with the low CTmax limit of tropical species (34–36°C). Tropical species showed a CTmin limit around 9°C similar to the maximum CTmin of temperate species (5–6°C). The maximum CTmin of deep sea species that occur in cold environments (2.5°C) matched the low CTmin values (3.2°C) of temperate species. Results also indicate that the energy required to activate the enzyme complex (Ei) involved in respiratory metabolism of ectotherms changes along the latitudinal gradient of temperature. PMID:26879464

  17. 75 FR 59696 - National Estuarine Research Reserve System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-28

    ... and storm water management, coastal and watershed development, and invasive species management. Since...: Estuarine Reserves Division, Office of Ocean and Coastal Resource Management, National Ocean Service... Approval and Availability of Revised Management Plans for the following National Estuarine...

  18. 75 FR 49887 - National Estuarine Research Reserve System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-16

    ... plan are designed to provide a framework that supports program integration for collaborative management...: Estuarine Reserves Division, Office of Ocean and Coastal Resource Management, National Ocean Service... Period for Revised Management Plans for the following National Estuarine Research Reserves:...

  19. 76 FR 16620 - National Estuarine Research Reserve System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-24

    ...: Estuarine Reserves Division, Office of Ocean and Coastal Resource Management, National Ocean Service... Period for Revised Management Plans for the following National Estuarine Research Reserves: ACE Basin, SC... of Ocean and Coastal Resource Management, National Ocean Service, National Oceanic and...

  20. 15 CFR 921.51 - Estuarine research guidelines.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... conducted in a manner consistent with Estuarine Research Guidelines developed by NOAA. (b) A summary of the... funds discussed in § 921.50(c). (c) The Estuarine Research Guidelines are reviewed annually by...

  1. 15 CFR 921.51 - Estuarine research guidelines.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... conducted in a manner consistent with Estuarine Research Guidelines developed by NOAA. (b) A summary of the... funds discussed in § 921.50(c). (c) The Estuarine Research Guidelines are reviewed annually by...

  2. 15 CFR 921.51 - Estuarine research guidelines.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... conducted in a manner consistent with Estuarine Research Guidelines developed by NOAA. (b) A summary of the... funds discussed in § 921.50(c). (c) The Estuarine Research Guidelines are reviewed annually by...

  3. Measuring the acute toxicity of estuarine sediments

    SciTech Connect

    DeWitt, T.H.; Swartz, R.C.; Lanberson, J.O.

    1989-01-01

    Estuarine sediments frequently are repositories and sources of anthropogenic contaminants. Toxicity is one method of assessing the environmental quality of sediments, yet because of the extreme range of salinities that characterize estuaries few infaunal organisms have both the physiological tolerance and sensitivity to chemical contaminants to serve in estuarine sediment toxicity tests. The study describes research on the estuarine burrowing amphipod, Eohaustorius estuarius Bosworth, 1973, whose survival was >95% in control sediments across a 2 to 28% salinity range over 10-d periods. E. estuarius also was acutely sensitive to low sediment concentrations of the polycyclic aromatic hydrocarbon, fluoranthene (LC50 approximately = 10.6 mg/kg), and its sensitivity to fluoranthene was not affected by salinity. E. estuarius was almost as sensitive as Rhepoxynius abronius to fluoranthene and to field-collected sediments from Puget Sound urban and industrial bays. E. estuarius was also more tolerant of very fine, uncontaminated sediments than R. abronius. Furthermore, E. estuarius was more sensitive to sediments spiked with fluoranthene than the freshwater amphipod, Hyalella azteca. E. estuarius, and possibly other estuarine haustoriid species, appears to be an excellent candidate for testing the acute toxicity if estuarine and marine sediments.

  4. A large bubble around the Crab Nebula

    NASA Technical Reports Server (NTRS)

    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.

  5. Ultraviolet studies of the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Talavera, A.

    2017-03-01

    The Crab Nebula (Messier 1) is one of the most observed sources with the XMM-Newton space telescope of ESA. The Crab and its related pulsar are a calibration source for the on-board X-rays cameras. There are around 80 observations between 2000 and 2015. In this observations, the XMM-Newton Optical and UV Monitor (OM) has also been used. We present a preliminary study of the Crab using images obtained the OM UV filters at 291, 231 and 212 nm. Photometric data for the pulsar (PSR0531+21), created in the supernova event of AD 1054 origin of the nebula, are also presented

  6. Design of the ILC Crab Cavity System

    SciTech Connect

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

    2007-08-15

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

  7. Crab Crossing Consideration for MEIC 2

    SciTech Connect

    S. Ahmed, Y.S. Derbenev, G.A. Krafft, Y. Zhang, A. Castilla, J.R. Delayen, S.D. Silva

    2011-03-01

    Crab crossing of colliding electron and ion beams is essential for accommodating the ultra high bunch repetition frequency in the conceptual design of MEIC – a high luminosity polarized electron-ion collider at Jefferson Lab. The scheme eliminates parasitic beam-beam interactions and avoids luminosity reduction by restoring head-on collisions at interaction points. In this paper, we report simulation studies of beam dynamics with crab cavities for MEIC design. The detailed study involves full 3-D simulations of particle tracking through the various configurations of crab cavities for evaluating the performance. To gain insight, beam and RF dominated fields with other parametric studies will be presented in the paper.

  8. 78 FR 40696 - Proposed Information Collection; Comment Request; Alaska Crab Cost Recovery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-08

    ... Crab Cost Recovery AGENCY: National Oceanic and Atmospheric Administration (NOAA), Commerce. ACTION... and Aleutian Islands (BSAI) Crab includes the Crab Rationalization (CR) Program, a limited access system that allocates BSAI Crab resources among harvesters, processors, and coastal communities....

  9. TOP DOWN CONTROL OF THE MICROBIAL LOOP IN ESTUARINE PHYTOPLANKTON

    EPA Science Inventory

    Top Down Control of the Microbial Loop in Estuarine Plankton (Abstract). To be presented at the 16th Biennial Conference of the Estuarine Research Foundation, ERF 2001: An Estuarine Odyssey, 4-8 November 2001, St. Pete Beach, FL. 1 p. (ERL,GB R846).

    We examined the effects...

  10. Gastric nematode diversity between estuarine and inland freshwater populations of the American alligator (Alligator mississippiensis, daudin 1802), and the prediction of intermediate hosts

    PubMed Central

    Tellez, Marisa; Nifong, James

    2014-01-01

    We examined the variation of stomach nematode intensity and species richness of Alligator mississippiensis from coastal estuarine and inland freshwater habitats in Florida and Georgia, and integrated prey content data to predict possible intermediate hosts. Nematode parasitism within inland freshwater inhabiting populations was found to have a higher intensity and species richness than those inhabiting coastal estuarine systems. This pattern potentially correlates with the difference and diversity of prey available between inland freshwater and coastal estuarine habitats. Increased consumption of a diverse array of prey was also correlated with increased nematode intensity in larger alligators. Parasitic nematodes Dujardinascaris waltoni, Brevimulticaecum tenuicolle, Ortleppascaris antipini, Goezia sp., and Contracaecum sp. were present in alligators from both habitat types. Dujardinascaris waltoni, B. tenuicolle, and O. antipini had a significantly higher abundance among inland inhabiting alligators than hosts from estuarine populations. Our findings also suggest that host specific nematode parasites of alligators may have evolved to infect multiple intermediate hosts, particularly fishes, crabs, and turtles, perhaps in response to the opportunistic predatory behaviors of alligators. PMID:25426417

  11. Metals in horseshoe crabs from Delaware Bay.

    PubMed

    Burger, J; Dixon, C; Shukla, T; Tsipoura, N; Jensen, H; Fitzgerald, M; Ramos, R; Gochfeld, M

    2003-01-01

    We examined the concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the eggs, leg muscle, and apodeme (carapace musculature) in horseshoe crabs ( Limulus polyphemus) from eight places on the New Jersey and Delaware sides of Delaware Bay to determine whether there were locational differences. Although there were locational differences, the differences were not great. Further, contaminant levels were generally low. The levels of contaminants found in horseshoe crabs were well below those known to cause adverse effects in the crabs themselves or in organisms that consume them or their eggs. Contaminant levels have generally declined in the eggs of horseshoe crabs from 1993 to 2001, suggesting that contaminants are not likely to be a problem for secondary consumers or a cause of their decline.

  12. Monitoring the Crab Nebula with LOFT

    NASA Technical Reports Server (NTRS)

    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.

  13. Why do fiddler crabs build chimneys?

    PubMed

    Slatyer, R A; Fok, E S Y; Hocking, R; Backwell, P R Y

    2008-12-23

    Chimneys are mud mounds built by fiddler crabs that encircle the entrance to their burrow. Their function in many species is unknown. In Uca capricornis, crabs of both sexes and all sizes build chimneys, but females do so disproportionately more often. There are no differences in the immediate physical or social environments between crabs with and without a chimney. Chimney owners spend less time feeding and more time underground than non-owners. We show experimentally that burrows with a chimney are less likely to be located by an intruder. It is possible that some crabs construct chimneys around their burrow to conceal the entrance and reduce the risk of losing it to an intruder.

  14. Wakefield Damping for the CLIC Crab Cavity

    SciTech Connect

    Ambattu, P.K.; Burt, G.; Dexter, A.C.; Carter, R.G.; Khan, V.; Jones, R.M.; Dolgashev, V.; /SLAC

    2011-12-01

    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.

  15. Epidemiology of bitter crab disease (Hematodinium sp.) in snow crabs Chionoecetes opilio from Newfoundland, Canada.

    PubMed

    Shields, Jeffrey D; Taylor, David M; Sutton, Stephen G; O'Keefe, Paul G; Ings, Danny W; Pardy, Amanda L

    2005-05-20

    The parasitic dinoflagellate Hematodinium sp. causes a condition known as bitter crab disease (BCD) in snow crabs Chionoecetes opilio and Tanner crabs C. bairdi. As the name of the condition implies, crabs infected with BCD are unmarketable due to their bitter flavor. We surveyed the distribution of BCD in 3 regions within the snow crab fishery of Newfoundland from 1997 to 2003. Over time, the disease has become firmly established in Conception and Bonavista Bays and persists at low levels on the Avalon fishing grounds. An epizootic occurred within Bonavista and Conception Bays in 1999 and persisted in Conception Bay in 2000, reaching prevalences of over 2% to 9% in trapped and trawled male crabs and from 19 to 26% in trawled and trapped female crabs, respectively. Infections were highest in females and small males, i.e. the unfished and pre-recruit portions of the fishery. In a mortality study, all of the naturally infected crabs died and 50% of the experimentally inoculated crabs died. Patterns in the molting cycle and prevalence of infection indicate that transmission occurs during the post-molt condition, and that overt infections probably develop 2 to 4 mo later with mortalities occurring at least 3 to 4 mo thereafter. The hydrography of this bay may have contributed to the epizootic as infections were centered within the deeper confines of the bay. Analysis of various abiotic factors uncovered a significant positive association between prevalence, depth and mud/sand substrates; the nature of this relationship was not apparent but may be related to diet or alternate hosts. Lastly, given the increase in BCD in snow crabs in Newfoundland, we recommend that fishery management programs for Chionoecetes fisheries employ non-selective gear to monitor for Hematodinium infections in female and juvenile crabs because these under-sampled members of the population may forewarn of impending recruitment declines that might otherwise remain unexplained.

  16. The visual ecology of fiddler crabs.

    PubMed

    Zeil, Jochen; Hemmi, Jan M

    2006-01-01

    With their eyes on long vertical stalks, their panoramic visual field and their pronounced equatorial acute zone for vertical resolving power, the visual system of fiddler crabs is exquisitely tuned to the geometry of vision in the flat world of inter-tidal mudflats. The crabs live as burrow-centred grazers in dense, mixed-sex, mixed-age and mixed-species colonies, with the active space of an individual rarely exceeding 1 m(2). The full behavioural repertoire of fiddler crabs can thus be monitored over extended periods of time on a moment to moment basis together with the visual information they have available to guide their actions. These attributes make the crabs superb subjects for analysing visual tasks and the design of visual processing mechanisms under natural conditions, a prerequisite for understanding the evolution of visual systems. In this review we show, on the one hand, how deeply embedded fiddler crab vision is in the behavioural and the physical ecology of these animals and, on the other hand, how their behavioural options are constrained by their perceptual limitations. Studying vision in fiddler crabs reminds us that vision has a topography, that it is context-dependent and pragmatic and that there are perceptual limits to what animals can know and therefore care about.

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

    PubMed

    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 < 0.05), while adult females, including ovigerous, inhabited the lower estuary, an area of major marine influence (p < 0.05). While juveniles look for estuarine waters due to the benefit from the shelter and abundance of food, ovigerous females migrate to areas of greater depth and higher 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.

  18. Molecular phylogeny of extant horseshoe crabs (Xiphosura, Limulidae) indicates Paleogene diversification of Asian species.

    PubMed

    Obst, Matthias; Faurby, Søren; Bussarawit, Somchai; Funch, Peter

    2012-01-01

    Horseshoe crabs are marine invertebrates well known for their exceptionally low rates of diversification during their entire evolutionary history. Despite the low species diversity in the group, the phylogenetic relationships among the extant species, especially among the three Asian species are still unresolved. Here we apply a new set of molecular genetic data in combination with a wide geographic sampling of the intra-specific diversity to reinvestigate the evolutionary history among the four living limulid xiphosurans. Our analysis of the intraspecific diversity reveals low levels of connectivity among Carcinoscorpius rotundicauda lineages, which can be explained by the estuarine-bound ecology of this species. Moreover, a clear genetic break across the Thai-Malay Peninsula suggests the presence of cryptic species in C. rotundicauda. The limulid phylogeny finds strong support for a monophyletic genus Tachypleus and a diversification of the three Asian species during the Paleogene period, with speciation events well separated in time by several million years. The tree topology suggests that the three Asian species originated in central South East Asia from a marine stem group that inhabited the shallow coastal waters between the Andaman Sea, Vietnam, and Borneo. In this region C. rotundicauda probably separated from the Tachypleus stem group by invading estuarine habitats, while Tachypleus tridentatus most likely migrated northeast along the Southern coast of China and towards Japan.

  19. Marine and estuarine protection: Programs and activities

    SciTech Connect

    Not Available

    1989-02-01

    The booklet describes: the mission of the current problems and threats to the coastal and marine waters of the US; the Office of Marine and Estuarine Protection of EPA; EPA's ocean dumping and plastics programs; EPA's point source control activities; near-coastal waters activities; and associated federal legislation.

  20. Estuarine Oceanography. CEGS Programs Publication Number 18.

    ERIC Educational Resources Information Center

    Wright, F. F.

    Estuarine Oceanography is one in a series of single-topic problem modules intended for use in undergraduate and earth science courses. Designed for those interested in coastal oceanography or limnology, the module is structured as a laboratory supplement for undergraduate college classes but should be useful at all levels. The module has two…

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

    PubMed Central

    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

  2. Effect of horseshoe crab spawning density on nest disturbance and exhumation of eggs: A simulation study

    USGS Publications Warehouse

    Smith, D.R.

    2007-01-01

    Because the Delaware Bay horseshoe crab (Limulus polyphemus) population is managed to provide for dependent species, such as migratory shorebirds, there is a need to understand the process of egg exhumation and to predict eggs available to foraging shorebirds. A simple spatial model was used to simulate horseshoe crab spawning that would occur on a typical Delaware Bay beach during spring tide cycles to quantify density-dependent nest disturbance. At least 20% of nests and eggs were disturbed for levels of spawning greater than one third of the average density in Delaware Bay during 2004. Nest disturbance increased approximately linearly as spawning density increased from one half to twice the 2004 level. As spawning density increased further, the percentage of eggs that were disturbed reached an asymptote of 70% for densities up to 10 times the density in 2004. Nest disturbance was heaviest in the mid beach zone. Nest disturbance precedes entrainment and begins the process of exhumation of eggs to surface sediments. Model predictions were combined with observations from egg surveys to estimate a snap-shot exhumation rate of 5-9% of disturbed eggs. Because an unknown quantity of eggs were exhumed and removed from the beach prior to the survey, cumulative exhumation rate was likely to have been higher than the snap-shot estimate. Because egg exhumation is density-dependent, in addition to managing for a high population size, identification and conservation of beaches where spawning horseshoe crabs concentrate in high densities (i.e., hot spots) are important steps toward providing a reliable food supply for migratory shorebirds. ?? 2007 Estuarine Research Federation.

  3. A comparative study of genetic variation between Chinese mitten crab ericheir sinensis and Hepu mitten crab E. hepuensis

    NASA Astrophysics Data System (ADS)

    Guangdong, Liu; Xiumei, Zhang; Tianxiang, Gao; Dong, Lou

    2002-10-01

    Horizonal starch gel electrophoresis was used to investigate the biochemical genetic structure of Chinese mitten crab Eriocheir sinensis and Hepu mitten crab E. hepuensis. Sixteen putative enzyme-coding loci were examined for forty-nine chinese mitten crabs and thirty-eight Hepu mitten crabs. Nine loci, AAT-1 *, AAT-2 *, G3PDH *, GPI *, IDHP-1 *, IDHP-2 *, MDH-1 *, MDH-2 * and PGM *, are polymorphic in Chinese mitten crab, and seven, AAT-1 *, AAT-2 *, GPI *, IDHP-1 *, MDH-1 *, MDH-2 * and PGM *, are polymorphic in Hepu mitten crab. The proportion of polymorphic loci and the expected heterozygosity are 0.562 5 and 0.080 3 for Chinese mitten crab, and 0.437 5 and 0.075 4 for Hepu mitten crab. The Nei’s genetic distance between two species is 0.002 4.

  4. Human effects on estuarine shoreline decadal evolution

    NASA Astrophysics Data System (ADS)

    Rilo, A.; Freire, P.; Ceia, R.; Mendes, R. N.; Catalão, J.; Taborda, R.

    2012-04-01

    Due to their sheltered conditions and natural resources, estuaries were always attractive to human activities (industrial, agriculture, residential and recreation). Consequently, the complex interactions between anthropogenic and natural drivers increase estuarine shoreline vulnerability to climate changes impacts. The environmental sustainability of these systems depends on a fragile balance between societal development and natural values that can be further disturbed by climate change effects. This challenging task for scientific community, managers and stakeholders can only be accomplished with interdisplinary approaches. In this context, it seems clear that estuarine management plans should incorporate the concept of change into the planning of policy decisions since these natural dynamic areas are often under human pressure and are recognized as sensitive to climate change effects. Therefore, the knowledge about historical evolution of estuarine shoreline is important to provide new insights on the spatial and temporal dimensions of estuarine change. This paper aims to present and discuss shoreline changes due to human intervention in Tagus estuary, located on the west coast of Portugal. Detailed margins cartography, in a 550m fringe (drawn inland from the highest astronomical tide line), was performed based on 2007 orthophotos (spatial resolution of 0.5 m) analysis. Several classification categories were considered, as urbanized areas, industrial, port and airport facilities, agriculture spaces, green areas and natural zones. The estuarine bed (area bellow the highest astronomical tide line) was also mapped (including human occupation, natural habitats, morpho-sedimentary units) based on the geographic information above and LANSAT 7 TM+ images using image processing techniques. Aerial photographs dated from 1944, 1946, 1948, 1955 and 1958 were analyzed for a set of pilot zones in order to fully understand the decadal shoreline change. Estuarine bed presents

  5. 50 CFR 680.6 - Crab economic data report (EDR).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab economic data report (EDR). 680.6... ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) SHELLFISH FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA General § 680.6 Crab economic data report (EDR). Persons participating in the CR crab fisheries...

  6. 50 CFR 680.21 - Crab harvesting cooperatives.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Crab harvesting cooperatives. 680.21... ZONE OFF ALASKA Management Measures § 680.21 Crab harvesting cooperatives. This section governs the formation and operation of crab harvesting cooperatives. The regulations in this section apply only to...

  7. 50 CFR 680.21 - Crab harvesting cooperatives.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab harvesting cooperatives. 680.21... ZONE OFF ALASKA Management Measures § 680.21 Crab harvesting cooperatives. This section governs the formation and operation of crab harvesting cooperatives. The regulations in this section apply only to...

  8. 50 CFR 680.21 - Crab harvesting cooperatives.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Crab harvesting cooperatives. 680.21... ZONE OFF ALASKA Management Measures § 680.21 Crab harvesting cooperatives. This section governs the formation and operation of crab harvesting cooperatives. The regulations in this section apply only to...

  9. 50 CFR 680.21 - Crab harvesting cooperatives.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Crab harvesting cooperatives. 680.21... ZONE OFF ALASKA Management Measures § 680.21 Crab harvesting cooperatives. This section governs the formation and operation of crab harvesting cooperatives. The regulations in this section apply only to...

  10. 50 CFR Table 5 to Part 680 - Crab Size Codes

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab Size Codes 5 Table 5 to Part 680 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION..., Table 5 Table 5 to Part 680—Crab Size Codes Size code Description 1 Standard or large sized crab or...

  11. The Radio Spectral Index of the Crab Nebula

    DTIC Science & Technology

    1997-11-20

    We present the results of a new, comprehensive investigation of the radio spectral index of the Crab Nebula supernova remnant. New data at 74 MHz are...thermal material in the Crab Nebula’s filaments. Apart from some possible renewed acceleration occurring in the wisps, the dominant accelerator of relativistic electrons in the Crab Nebula is the pulsar itself.

  12. 50 CFR Table 2 to Part 680 - Crab Species Code

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., Table 2 Table 2 to Part 680—Crab Species Code Species code Common name Scientific name 900 Box Lopholithodes mandtii. 910 Dungeness Cancer magister. 921 Red king crab Paralithodes camtshaticus. 922 Blue king... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Crab Species Code 2 Table 2 to Part...

  13. 50 CFR Table 2 to Part 680 - Crab Species Code

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., Table 2 Table 2 to Part 680—Crab Species Code Species code Common name Scientific name 900 Box Lopholithodes mandtii. 910 Dungeness Cancer magister. 921 Red king crab Paralithodes camtshaticus. 922 Blue king... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Crab Species Code 2 Table 2 to Part...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seven blue crab processing plants were sampled to determine the prevalence and sources of Listeria spp. and L. monocytogenes for two years (2006-2007). A total of 488 raw crab, 624 crab meat, and 624 environmental samples were tested by molecular and culture-based standard methods. Presumptive Liste...

  15. Positive feedback fishery: Population consequences of `crab-tiling' on the green crab Carcinus maenas

    NASA Astrophysics Data System (ADS)

    Sheehan, E. V.; Thompson, R. C.; Coleman, R. A.; Attrill, M. J.

    2008-11-01

    Collection of marine invertebrates for use as fishing bait is a substantial activity in many parts of the world, often with unknown ecological consequences. As new fisheries develop, it is critical for environmental managers to have high quality ecological information regarding the potential impacts, in order to develop sound management strategies. Crab-tiling is a largely unregulated and un-researched fishery, which operates commercially in the south-west UK. The target species is the green crab Carcinus maenas. Those crabs which are pre-ecdysis and have a carapace width greater than 40 mm are collected to be sold to recreational anglers as bait. Collection involves laying artificial structures on intertidal sandflats and mudflats in estuaries. Crabs use these structures as refugia and are collected during low tide. However, the effect that this fishery has on populations of C. maenas is not known. The impact of crab-tiling on C. maenas population structure was determined by sampling crabs from tiled estuaries and non-tiled estuaries using baited drop-nets. A spatially and temporarily replicated, balanced design was used to compare crab abundance, sizes and sex ratios between estuaries. Typically, fisheries are associated with a reduction in the abundance of the target species. Crab-tiling, however, significantly increased C. maenas abundance. This was thought to be a result of the extra habitat in tiled estuaries, which probably provides protection from natural predators, such as birds and fish. Although crabs were more abundant in tiled estuaries than non-tiled estuaries, the overall percentage of reproductively active crabs in non-tiled estuaries was greater than in tiled estuaries. As with most exploited fisheries stocks, crabs in exploited (tiled) estuaries tended to be smaller, with a modal carapace width of 20-29 mm rather than 30-39 mm in non-tiled estuaries. The sex ratio of crabs however; was not significantly different between tiled and non

  16. Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (Pacific Southwest): Brown rock crab, red rock crab, and yellow crab

    SciTech Connect

    Carroll, J.C. ); Winn, R.N. )

    1989-12-01

    Species profiles are literature summaries of the taxonomy, morphology, distribution, life history, habitats, and environmental requirements of coastal species of fishes and aquatic invertebrates. They are designed to assist in environmental impact assessment. Rock crab'' is the common name designating three similar species of edible crabs: brown rock crab (Cancer antennarius), red rock crab (C. productus), and yellow crab (C. anthonyi). The three species co-occur in shallow coastal waters throughout the Pacific Southwest region. The yellow crab is most common in southern California on sand substrate, and the red rock crab in northernmost areas on rock or gravel substrates; the brown rock crab occurs on rock or sand substrates in all areas. Rock crabs are sought commercially to fill an increasing market demand for whole crabs that approached 2 million pounds annually in 1986. Most of the catch comes from the region of Morro Bay south to Los Angeles, including the Channel Islands. Egg-bearing females are commonly found during winter, although they may occur throughout the year.Rock crabs go through five zoeal stages and one megalopal stage during a larval period that generally requires 90--120 days. Metamorphosis and settlement of the first crab stage is on either sand or rock, and crabs may reach maturity within 1--2 years. All three species are predators on a variety of shelled mollusks, but are also considered scavengers. They are a major food for many commercially and recreationally important fishes, as well as for the threatened southern sea otter, Enhydra lutris. 63 refs., 6 figs., 1 tab.

  17. Novel Geometries for the LHC Crab Cavity

    SciTech Connect

    B. Hall,G. Burt,C. Lingwood,Robert Rimmer,Haipeng Wang; Hall, B.; Burt, G.; Lingwood, C.; Rimmer, Robert; Wang, Haipeng

    2010-05-01

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

  18. Novel Geometries for the LHC Crab Cavity

    SciTech Connect

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

    2010-05-23

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

  19. 75 FR 42068 - Evaluation of State Coastal Management Programs and National Estuarine Research Reserves

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-20

    ... National Estuarine Research Reserves AGENCY: National Oceanic and Atmospheric Administration (NOAA), Office... intent to evaluate the performance of the Elkhorn Slough (California) National Estuarine Research Reserve. The National Estuarine Research Reserve evaluation will be conducted pursuant to sections 312 and...

  20. Spontaneous alternation and locomotor activity in three species of marine crabs: green crab (Carcinus maenas), blue crab (Callinectes sapidus), and fiddler crab (Uca pugnax).

    PubMed

    Balcı, Fuat; Ramey-Balcı, Patricia A; Ruamps, Perrine

    2014-02-01

    Spontaneous alternation refers to the tendency of organisms to explore places that they have least recently visited. Our previous work showed that alternation performance of Carcinus maenas (invasive European green crab) was significantly higher than Callinectes sapidus (native blue crab), and chance level performance (Ramey, P. A., Teichman, E., Oleksiak, J., & Balcı, F. [2009]. Spontaneous alternation in marine crabs: Invasive versus native species. Behavioural Processes, 82, 51-55.). In the current study, we first tested the robustness of these findings in the absence of visual cues, longer test durations, and wider maze dimensions. These manipulations enabled us to determine whether these two crab species relied on the visual cues provided during the spontaneous alternation task in our prior work, and allowed for better characterization of their exploratory activity in the maze. Our original findings were reproduced in the present study under these new task conditions, suggesting no role for visual cues during alternation, and emphasizing the robustness and generalizability of the corresponding interspecies differences in alternation performance. We also tested whether the lower alternation performance of C. sapidus also applied to another native crab species, Uca pugnax (fiddler crab). Spontaneous alternation performance of U. pugnax was significantly lower than C. maenas but indistinguishable from C. sapidus. Finally, we examined whether the potentially higher inherent risk-sensitivity of C. sapidus could have contributed to their lower alternation performance by testing C. maenas in the presence of a larger natural predator (stressor). Higher risk sensitivity presumably induced by the stressor led to locomotor activity patterns that better resembled those of C. sapidus, however the resultant reduction in alternation performance was not statistically significant.

  1. Distortion of Crabbed Bunch Due to the Electron Cloud

    SciTech Connect

    Wang, L; Raubenheimer, T.; /SLAC

    2008-05-28

    In order to improve the luminosity, two crab cavities have been installed in KEKB HER and LER [1]. Since there is only one crab cavity in each ring, the crab cavity generates a horizontally titled bunch along the whole ring. The achieved specific luminosity with crabbed bunch is higher, but it is not as high as that from beam-beam simulation [2]. One of the suspicions is the electron cloud. The electron cloud in LER (positron beam) may distort the crabbed bunch and cause the luminosity drop. This note briefly estimates the bunch shape distortion due to the electron cloud in KEKB LER.

  2. Estuarine turbidity, flushing, salinity, and circulation

    NASA Technical Reports Server (NTRS)

    Pritchard, D. W.

    1972-01-01

    The effects of estuarine turbidity, flushing, salinity, and circulation on the ecology of the Chesapeake Bay are discussed. The sources of fresh water, the variations in salinity, and the circulation patterns created by temperature and salinity changes are analyzed. The application of remote sensors for long term observation of water temperatures is described. The sources of sediment and the biological effects resulting from increased sediments and siltation are identified.

  3. Green crab (Carcinus maenas) foraging efficiency reduced by fast flows.

    PubMed

    Robinson, Elizabeth M; Smee, Delbert L; Trussell, Geoffrey C

    2011-01-01

    Predators can strongly influence prey populations and the structure and function of ecosystems, but these effects can be modified by environmental stress. For example, fluid velocity and turbulence can alter the impact of predators by limiting their environmental range and altering their foraging ability. We investigated how hydrodynamics affected the foraging behavior of the green crab (Carcinus maenas), which is invading marine habitats throughout the world. High flow velocities are known to reduce green crab predation rates and our study sought to identify the mechanisms by which flow affects green crabs. We performed a series of experiments with green crabs to determine: 1) if their ability to find prey was altered by flow in the field, 2) how flow velocity influenced their foraging efficiency, and 3) how flow velocity affected their handling time of prey. In a field study, we caught significantly fewer crabs in baited traps at sites with fast versus slow flows even though crabs were more abundant in high flow areas. This finding suggests that higher velocity flows impair the ability of green crabs to locate prey. In laboratory flume assays, green crabs foraged less efficiently when flow velocity was increased. Moreover, green crabs required significantly more time to consume prey in high velocity flows. Our data indicate that flow can impose significant chemosensory and physical constraints on green crabs. Hence, hydrodynamics may strongly influence the role that green crabs and other predators play in rocky intertidal communities.

  4. Green Crab (Carcinus maenas) Foraging Efficiency Reduced by Fast Flows

    PubMed Central

    Robinson, Elizabeth M.; Smee, Delbert L.; Trussell, Geoffrey C.

    2011-01-01

    Predators can strongly influence prey populations and the structure and function of ecosystems, but these effects can be modified by environmental stress. For example, fluid velocity and turbulence can alter the impact of predators by limiting their environmental range and altering their foraging ability. We investigated how hydrodynamics affected the foraging behavior of the green crab (Carcinus maenas), which is invading marine habitats throughout the world. High flow velocities are known to reduce green crab predation rates and our study sought to identify the mechanisms by which flow affects green crabs. We performed a series of experiments with green crabs to determine: 1) if their ability to find prey was altered by flow in the field, 2) how flow velocity influenced their foraging efficiency, and 3) how flow velocity affected their handling time of prey. In a field study, we caught significantly fewer crabs in baited traps at sites with fast versus slow flows even though crabs were more abundant in high flow areas. This finding suggests that higher velocity flows impair the ability of green crabs to locate prey. In laboratory flume assays, green crabs foraged less efficiently when flow velocity was increased. Moreover, green crabs required significantly more time to consume prey in high velocity flows. Our data indicate that flow can impose significant chemosensory and physical constraints on green crabs. Hence, hydrodynamics may strongly influence the role that green crabs and other predators play in rocky intertidal communities. PMID:21687742

  5. Modeling Crabbing Dynamics in an Electron-Ion Collider

    SciTech Connect

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

    2015-09-01

    A local crabbing scheme requires π/2 (mod π) horizontal betatron phase advances from an interaction point (IP) to the crab cavities on each side of it. However, realistic phase advances generated by sets of quadrupoles, or Final Focusing Blocks (FFB), between the crab cavities located in the expanded beam regions and the IP differ slightly from π/2. To understand the effect of crabbing on the beam dynamics in this case, a simple model of the optics of the Medium Energy Electron-Ion Collider (MEIC) including local crabbing was developed using linear matrices and then studied numerically over multiple turns (1000 passes) of both electron and proton bunches. The same model was applied to both local and global crabbing schemes to determine the linear-order dynamical effects of the synchro-betatron coupling induced by crabbing.

  6. Evolution of metabolomics profile of crab paste during fermentation.

    PubMed

    Chen, Daian; Ye, Yangfang; Chen, Juanjuan; Yan, Xiaojun

    2016-02-01

    Crab paste is regularly consumed by people in the coastal area of China. The fermentation time plays a key role on the quality of crab paste. Here, we investigated the dynamic evolution of metabolite profile of crab paste during fermentation by combined use of NMR spectroscopy and multivariate data analysis. Our results showed that crab paste quality was significantly affected by fermentation. The quality change was manifested in the decline of lactate, betaine, taurine, trimethylamine-N-oxide, trigonelline, inosine, adenosine diphosphate, and 2-pyridinemethanol, and in the fluctuation of a range of amino acids as well as in the accumulation of glutamate, sucrose, formate, acetate, trimethylamine, and hypoxanthine. Trimethylamine production and its increased level with fermentation could be considered as a freshness index of crab paste. These results contribute to quality assessment of crab paste and confirm the metabolomics technique as a useful tool to provide important information on the crab paste quality.

  7. Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest). Brown Rock Crab, Red Rock Crab, and Yellow Crab

    DTIC Science & Technology

    1989-12-01

    distinguished by a slender abdomen and Two other large Cancer species, the Dungeness crab mature females by a broad abdomen that is often hirsute (C. magister...crab lives almost exclusively on animals often remained in one location for scveral days. sandy substrata; consequently the "rock crab" designation is... animals McConaugha, J.R. 1985. Nutrition and larval growth. of the Pacific coast. Dover Publications, New York. Pages 127-154 in A.M. Wenner, ed

  8. Impact of a major cyclone on a southeast African estuarine lake system

    NASA Astrophysics Data System (ADS)

    Forbes, A. T.; Cyrus, D. P.

    The St Lucia lake and estuarine system in northern Natal, South Africa was struck by Cyclone Domoina on 31 January 1984. This is the only cyclone known to have traversed part of South Africa. The ensuing flood levels in the St Lucia system (which have been exceeded perhaps only one other time in recorded history) provided an opportunity to assess the effect of a major disturbance on a subtropical estuarine system. Major geomorphological changes occurred in the mouth area where all man-made structures were obliterated. The two river channels were scoured from 2-3 m to 10-14 m in depth and widened by up to 300 m, while the shoreline between the two channels retreated in places up to 100 m. An estimated 16∗10 6 m 3 of sediment were removed from the lower reaches of the system including areas of mangrove and Phragmites australis swamp. One-metre tall mangrove saplings died following inundation lasting days to weeks. Effects on the fauna included redistribution of the tanaid Apseudes digitalis, the mysid Mesopodopsis africana, the copepod Pseudodiaptomus stuhlmanni, the polychaete Scololepis squamata and the bivalve Solen cylindraceus, all typical lake species which appeared in the tidal channel linking the lake with the sea. Responses of other species such as the penaeid prawns, the crab Scylla serrata and the sole Solea bleekeri suggested that physiological tolerance, extended larval or juvenile recruitment periods and prey switching minimized long-term flood effects. No large-scale mortalities were noted, and the absence of a temperature shock is considered to be a significant feature.

  9. 50 CFR 648.263 - Red crab possession and landing restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., transport, land, sell, trade, or barter, up to 500 lb (226.8 kg) of red crab, or its equivalent in weight as... restrictions. (a) Vessels issued limited access red crab permits. (1) (2) Conversion to whole crab weight. (i... recovery rate is 64 percent of a whole red crab, which is equal to the weight of red crab half...

  10. 50 CFR 648.263 - Red crab possession and landing restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., transport, land, sell, trade, or barter, up to 500 lb (226.8 kg) of red crab, or its equivalent in weight as... restrictions. (a) Vessels issued limited access red crab permits. (1) (2) Conversion to whole crab weight. (i... recovery rate is 64 percent of a whole red crab, which is equal to the weight of red crab half...

  11. Extractable organohalogens (EOX) in sediment and biota collected at an estuarine marsh near a former chloralkali facility

    SciTech Connect

    Kannan, K.; Giesy, J.P.; Kawano, Masahide; Kashima, Yuji; Matsui, Mitsuaki

    1999-04-01

    Extractable, organically bound chlorine (EOCl), which is determined by neutron activation analysis (NAA), has been used as a measure of pollution by chlorinated organics. In this study, the concentrations and distribution of extractable organohalogens (EOX = EOCl + EOBr + EOl) were measured in sediment, blue crab, fishes, birds, and terrapin collected at an estuarine marsh and a nearby creek contaminated by the disposal of wastes from a former chloralkali facility. The concentrations of the organohalogens were in the order of EOCl {much_gt} EOBr > EOl. The sediment EOCl concentration was comparable to those reported for sediments at sites that have been contaminated by the disposal of bleached kraft pulp mill effluents. The concentrations of EOCl measured in the tissues of blue crab, fishes, and birds were higher than any values previously reported. The absolute concentrations of EOCl coupled with its elevated proportions relative to the concentrations of EOBr or EOl in biota suggest that wastes from the chloralkali processes are a potential source of chlorinated organics present in the environment.

  12. Copper, zinc and cadmium in benthic organisms from the Java Sea and estuarine and coastal areas around East Java

    NASA Astrophysics Data System (ADS)

    Everaarts, J. M.; Boon, J. P.; Kastoro, W.; Fischer, C. V.; Razak, H.; Sumanta, I.

    A study was made of the concentrations of copper, zinc and cadmium in benthic organisms, representing the phyla Mollusca, Arthropoda, Echinodermata and Pisces, from the riverine and estuarine areas of the rivers Brantas and Solo (East Java) and the adjacent coastal area. Moreover, an assessment was made of the contamination of the benthic biota with these elements in the Java Sea and Bali Sea. Benthic organisms show a species-specific uptake pattern for each element. Compared to the same type of animals from estuaries and coastal areas in temperate regions of western Europe, the concentrations of cadmium are considerably higher, while copper and zinc concentrations are somewhat lower. There is no general trend in concentration levels of the metals in specimens from rivers, estuaries, coastal zone and open sea. In some groups of organisms ( e.g. shrimp, starfish) the concentrations of copper and zinc are highest in specimens from rivers and estuaries. In contrast, cadmium concentration levels in e.g. crab, shrimp and squid are lowest in riverine and estuarine areas. Significant differences in metal concentrations in these organisms were found between the dry monsoon period (July, August) and the beginning of the wet monsoon (November, December). No relationship existed between the metal concentration of the organisms and the silt fraction of the sediment (grain size < 63 μm) or the bulk sediment.

  13. Ocean acidification impairs crab foraging behaviour

    PubMed Central

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

    2015-01-01

    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. PMID:26108629

  14. Ocean acidification impairs crab foraging behaviour.

    PubMed

    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.

  15. [Biologically Active Peptides of King Crab Hepatopancreas].

    PubMed

    Bogdanov, V V; Berezin, B B; Il'ina, A P; Yamskova, V P; Yamskov, I A

    2015-01-01

    Substances of a peptide nature isolated from the hepatopancreas of the king crab Paralithodes camtschaticus exhibited physicochemical properties and membranotropic and specific activities similar to those of membranotropic homeostatic tissue-specific bioregulators previously found in different mammalian and plant tissues. Their biological effect on vertebrate tissues was demonstrated on a model of roller organotypic cultivation of Pleurodeles waltl newt liver tissue.

  16. A HYPERSPECTRAL VIEW OF THE CRAB NEBULA

    SciTech Connect

    Charlebois, M.; Drissen, L.; Bernier, A.-P.; Grandmont, F.; Binette, L. E-mail: ldrissen@phy.ulaval.c

    2010-05-15

    We have obtained spatially resolved spectra of the Crab nebula in the spectral ranges 450-520 nm and 650-680 nm, encompassing the H{beta}, [O III] {lambda}4959, {lambda}5007, H{alpha}, [N II] {lambda}6548, {lambda}6584, and [S II] {lambda}6717, {lambda}6731 emission lines, with the imaging Fourier transform spectrometer SpIOMM at the Observatoire du Mont-Megantic's 1.6 m telescope. We first compare our data with published observations obtained either from a Fabry-Perot interferometer or from a long-slit spectrograph. Using a spectral deconvolution technique similar to the one developed by Cadez et al., we identify and resolve multiple emission lines separated by large Doppler shifts and contained within the rapidly expanding filamentary structure of the Crab. This allows us to measure important line ratios, such as [N II]/H{alpha}, [S II]/H{alpha}, and [S II] {lambda}6717 /[S II] {lambda}6731 of individual filaments, providing a new insight on the SE-NW asymmetry in the Crab. From our analysis of the spatial distribution of the electronic density and of the respective shocked versus photoionized gas components, we deduce that the skin-less NW region must have evolved faster than the rest of the nebula. Assuming a very simple expansion model for the ejecta material, our data provide us with a complete tridimensional view of the Crab.

  17. The CMS Remote Analysis Builder (CRAB)

    SciTech Connect

    Spiga, D.; Cinquilli, M.; Servoli, L.; Lacaprara, S.; Fanzago, F.; Dorigo, A.; Merlo, M.; Farina, F.; Fanfani, A.; Codispoti, G.; Bacchi, W.; /INFN, Bologna /Bologna U /CERN /INFN, CNAF /INFN, Trieste /Fermilab

    2008-01-22

    The CMS experiment will produce several Pbytes of data every year, to be distributed over many computing centers geographically distributed in different countries. Analysis of this data will be also performed in a distributed way, using grid infrastructure. CRAB (CMS Remote Analysis Builder) is a specific tool, designed and developed by the CMS collaboration, that allows a transparent access to distributed data to end physicist. Very limited knowledge of underlying technicalities are required to the user. CRAB interacts with the local user environment, the CMS Data Management services and with the Grid middleware. It is able to use WLCG, gLite and OSG middleware. CRAB has been in production and in routine use by end-users since Spring 2004. It has been extensively used in studies to prepare the Physics Technical Design Report (PTDR) and in the analysis of reconstructed event samples generated during the Computing Software and Analysis Challenge (CSA06). This involved generating thousands of jobs per day at peak rates. In this paper we discuss the current implementation of CRAB, the experience with using it in production and the plans to improve it in the immediate future.

  18. Search for excess showers from Crab Nebula

    NASA Technical Reports Server (NTRS)

    Kirov, I. N.; Stamenov, J. N.; Ushev, S. Z.; Janminchev, V. D.; Aseikin, V. S.; Nikolsky, S. I.; Nikolskaja, N. M.; Yakovlev, V. I.; Morozov, A. E.

    1985-01-01

    The arrival directions of muon poor showers registrated in the Tien Shan experiment during an effective running time about I,8.IO(4)h were analyzed. It is shown that there is a significant excess of these showers coming the direction of Crab Nebula.

  19. Corneal laceration caused by river crab

    PubMed Central

    Vinuthinee, Naidu; Azreen-Redzal, Anuar; Juanarita, Jaafar; Zunaina, Embong

    2015-01-01

    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. PMID:25678769

  20. HUBBLE CAPTURES DYNAMICS OF CRAB NEBULA

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A new sequence of Hubble Space Telescope images of the remnant of a tremendous stellar explosion is giving astronomers a remarkable look at the dynamic relationship between the tiny Crab Pulsar and the vast nebula that it powers. This picture shows a Hubble Space Telescope image of the inner parts of the Crab. The pulsar itself is visible as the left of the pair of stars near the center of the frame. Surrounding the pulsar is a complex of sharp knots and wisp-like features. This image is one of a sequence of Hubble images taken over the course of several months. This sequence shows that the inner part of the Crab Nebula is far more dynamic than previously understood. The Crab literally 'changes it stripes' every few days as these wisps stream away from the pulsar at half the speed of light. The Hubble Space Telescope photo was taken Nov. 5, 1995 by the Wide Field and Planetary Camera 2 at a wavelength of around 550 nanometers, in the middle of the visible part of the electromagnetic spectrum. Credit: Jeff Hester and Paul Scowen (Arizona State University), and NASA

  1. Power coupler for the ILC crab cavity

    SciTech Connect

    Burt, G.; Dexter, A.; Jenkins, R.; Beard, C.; Goudket, P.; McIntosh, P.A.; Bellantoni, Leo; /Fermilab

    2007-06-01

    The ILC crab cavity will require the design of an appropriate power coupler. The beam-loading in dipole mode cavities is considerably more variable than accelerating cavities, hence simulations have been performed to establish the required external Q. Simulations of a suitable coupler were then performed and were verified using a normal conducting prototype with variable coupler tips.

  2. A Hyperspectral View of the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Charlebois, M.; Drissen, L.; Bernier, A.-P.; Grandmont, F.; Binette, L.

    2010-05-01

    We have obtained spatially resolved spectra of the Crab nebula in the spectral ranges 450-520 nm and 650-680 nm, encompassing the Hβ, [O III] λ4959, λ5007, Hα, [N II] λ6548, λ6584, and [S II] λ6717, λ6731 emission lines, with the imaging Fourier transform spectrometer SpIOMM at the Observatoire du Mont-Mégantic's 1.6 m telescope. We first compare our data with published observations obtained either from a Fabry-Perot interferometer or from a long-slit spectrograph. Using a spectral deconvolution technique similar to the one developed by Čadež et al., we identify and resolve multiple emission lines separated by large Doppler shifts and contained within the rapidly expanding filamentary structure of the Crab. This allows us to measure important line ratios, such as [N II]/Hα, [S II]/Hα, and [S II] λ6717 /[S II] λ6731 of individual filaments, providing a new insight on the SE-NW asymmetry in the Crab. From our analysis of the spatial distribution of the electronic density and of the respective shocked versus photoionized gas components, we deduce that the skin-less NW region must have evolved faster than the rest of the nebula. Assuming a very simple expansion model for the ejecta material, our data provide us with a complete tridimensional view of the Crab.

  3. Coastal and Estuarine Waters: Light Behavior. Coastal and Estuarine Waters: Optical Sensors and Remote Sensing.

    EPA Science Inventory

    This article summarizes the use of remote sensing techniques and technology to monitor coastal and estuarine waters. These waters are rich in mineral particles stirred up from the seabed by tides and waves and dissolved organic matter transported by rivers. The majority of the li...

  4. 15 CFR 921.3 - National Estuarine Research Reserve System biogeographic classification scheme and estuarine...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE OCEAN AND COASTAL RESOURCE MANAGEMENT NATIONAL ESTUARINE... chosen to reflect regional differences and to include a variety of ecosystem types. A biogeographic classification scheme based on regional variations in the nation's coastal zone has been developed....

  5. Estuarine consumers utilize marine, estuarine and terrestrial organic matter and provide connectivity among these food webs

    EPA Science Inventory

    The flux of organic matter (OM) across ecosystem boundaries can influence estuarine food web dynamics and productivity. However, this process is seldom investigated taking into account all the adjacent ecosystems (e.g. ocean, river, land) and different hydrological settings (i.e....

  6. Burrow surveillance in fiddler crabs. I. Description of behaviour.

    PubMed

    Hemmi, Jan M; Zeil, J

    2003-11-01

    When defending resources, animals need to reliably detect and identify potential competitors. Animals that live at high population densities would be expected to be efficient in this aspect of resource defence since the time lost in false alarms could be substantial and the failure of identifying a competitor could be very costly. How does an animal decide whether another animal is or is not a threat to a resource or a territory? Fiddler crabs [Uca vomeris (McNeill)] operate from burrows that they guard and defend vigorously against other crabs. The crabs live in dense populations, with many animals inhabiting one square metre of mudflat. We describe here the behavioural responses of foraging crabs to repeated presentations of small crab-like dummies approaching their burrows. We explore the relationship between the probability and the timing of burrow defence responses, the crab's behavioural state, and the visual appearance and direction of approach of the dummies. We find that the probability of response of resident crabs is independent of the relative position of crab and dummy but is strongly affected by the dummy's position and movement direction relative to the crab's burrow. The critical stimuli are the dummy's distance from the crab's burrow and whether the dummy is moving towards the burrow or not. The response distance (dummy-burrow distance) increases with the crab's own distance from the burrow, indicating that the crabs modify their assessment of threat depending on their own distance away from the burrow. Differences in dummy size and brightness do not affect the probability or the timing of the response. We discuss these results in the context of fiddler crab social life and, in a companion paper, identify the visual and non-visual cues involved in burrow defence.

  7. OVERVIEW OF GIS APPLICATIONS IN ESTUARINE MONITORING AND ASSESSMENT RESEARCH

    EPA Science Inventory

    Geographic information systems (GIS) tools are now considered integral in estuarine monitoring and assessment research. A synopsis is presented of our estuarine applications of GIS in the Northeast region of the U.S. The applications discussed cover sample site selection, support...

  8. Estuarine 'collaboratories:' regional and global perspectives (Invited)

    NASA Astrophysics Data System (ADS)

    Baptista, A. M.; Needoba, J. A.; Davis, M.; Leinen, M.

    2013-12-01

    There is an urgent need to anticipate and manage environmental changes in estuaries, as these critical ecosystems provide services that are essential for regional and global sustainability. Collaboratively designed and operated estuarine observation and prediction systems are progressively enabling long-term and high-resolution characterizations of estuarine variability and function, thus providing a powerful foundation for stewardship activities. The benefits of these 'collaboratories' have been demonstrated regionally in various estuaries, and their broader scale potential is being explored through an emerging national and international initiative. The first part of this presentation will address the lessons learned from SATURN (http://www.stccmop.org), a mature multi-institutional 'collaboratory' for the Columbia River estuary. SATURN innovatively integrates sensors, models, flows of information, and communities of practice. This integration has fueled advances in understanding and prediction of the estuary as a complex and highly variable bioreactor, subject to shifts from global climate change and from evolving regional uses. Our focus will be on describing the aspects of the design and practice that make SATURN transformative as a scientific and management-support tool at a regional scale. The second part of the presentation will address the translation of lessons learned from and beyond SATURN into requirements for a global network of estuarine observation and prediction systems. 'Our Global Estuary' is an initiative designed to create and use such a network, to maximize the aggregate potential of estuaries as sentinels and key players in global sustainability. We will report on the main recommendations of the first planning workshop for this initiative, which will take place on October 2013.

  9. Dispersal, Genetic Differentiation and Speciation in Estuarine Organisms

    NASA Astrophysics Data System (ADS)

    Bilton, D. T.; Paula, J.; Bishop, J. D. D.

    2002-12-01

    For some of their occupants, estuaries represent spatially discrete habitats, isolated from each other by barriers to dispersal or physiological tolerance. We present contrasting strategies for the retention or export of larvae from their estuary of origin, and consider the implications these have on population structure and divergence. Reported patterns of genetic differentiation and inferred gene flow in estuarine taxa (principally animals) are reviewed, and difficulties in the interpretation of existing genetic data discussed. Species concepts and models of speciation relevant to estuaries are outlined, and patterns of speciation of estuarine taxa reviewed. It is concluded that estuarine environments tend to restrict gene flow and impose distinct selective regimes, generating physiologically adapted populations divergent from their marine counterparts, and the potential for in situ speciation in complete or partial isolation. The resulting taxa may represent sibling or cryptic species groups of truly estuarine origin, rather than simply estuarine populations of marine eurytopes.

  10. Applications of remote sensing to estuarine management

    NASA Technical Reports Server (NTRS)

    Munday, J. C., Jr.; Gordon, H. H.; Hennigar, H. F.

    1977-01-01

    Remote sensing was used in the resolution of estuarine problems facing federal and Virginia governmental agencies. A prototype Elizabeth River Surface Circulation Atlas was produced from photogrammetry to aid in oil spill cleanup and source identification. Aerial photo analysis twice led to selection of alternative plans for dredging and spoil disposal which minimized marsh damage. Marsh loss due to a mud wave from a highway dyke was measured on sequential aerial photographs. An historical aerial photographic sequence gave basis to a potential Commonwealth of Virginia legal claim to accreting and migrating coastal islands.

  11. Ghost fishing activity in derelict blue crab traps in Louisiana.

    PubMed

    Anderson, Julie A; Alford, Amy B

    2014-02-15

    Derelict crab traps impact the coastal ecosystem through continued catch of target species and species of conservation, economic, or recreational importance. During volunteer-supported crab trap cleanups in 2012 and 2013, we quantified ghost fishing activity in derelict crab traps in coastal Louisiana through a citizen scientist program. Volunteers removed 3607 derelict traps during these events, and over 65% of traps analyzed by citizen scientists were actively ghost fishing. Additionally, volunteers identified 19 species enmeshed in derelict traps, including a combination of fresh and saltwater species. We also detected a significant difference in the number of blue crab in actively ghost fishing derelict traps across removal locations with estimated catches varying between 2.4 and 3.5 crabs/trap. Our instantaneous estimates of ghost fishing activity are greater than those previously thought in Louisiana, further justifying current derelict crab trap prevention and removal extension and outreach programs in Louisiana and throughout the Gulf of Mexico.

  12. Accumulation and depuration of pectenotoxins in brown crab Cancer pagurus

    NASA Astrophysics Data System (ADS)

    Li, Zhaoxin

    2009-06-01

    Pectenotoxins (PTXs) are a group of marine algal toxins. In this study, the accumulation and depuration of pectenotoxins in brown crab Cancer pagurus were investigated. Crabs were fed with toxic blue mussels Mytilus edulis for 21 days and then depurated for 42 days. Toxins were extracted with methanol from the digestive glands of contaminated crabs, uncontaminated crabs (control group) and from blue mussels for comparison. Extracts were analyzed by liquid chromatograph coupled with tandem mass spectrometry (LC-MS-MS). The concentrations of PTX-2, PTX-2 SA, 7- epi-PTX-2 SA, and PTX-12 were analyzed in two batches of toxic blue mussels and the crabs. A one-compartment model was applied to describe the depuration of PTXs. The half-life of PTXs was estimated to be 6-7.5 days. After depuration for 42 days, the amount of PTXs measured in the crab digestive glands was less than 1 μg/kg.

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

    PubMed Central

    Garcia, Miranda M.; Smee, Delbert L.

    2017-01-01

    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. PMID:28265512

  14. Status of LHC crab activity simulations and beam studies

    SciTech Connect

    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.

    2009-05-04

    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.

  15. Challenging paradigms in estuarine ecology and management

    NASA Astrophysics Data System (ADS)

    Elliott, M.; Whitfield, A. K.

    2011-10-01

    For many years, estuarine science has been the 'poor relation' in aquatic research - freshwater scientists ignored estuaries as they tended to get confused by salt and tides, and marine scientists were more preoccupied by large open systems. Estuaries were merely regarded by each group as either river mouths or sea inlets respectively. For the past four decades, however, estuaries (and other transitional waters) have been regarded as being ecosystems in their own right. Although often not termed as such, this has led to paradigms being generated to summarise estuarine structure and functioning and which relate to both the natural science and management of these systems. This paper defines, details and affirms these paradigms that can be grouped into those covering firstly the science (definitions, scales, linkages, productivity, tolerances and variability) and secondly the management (pressures, valuation, health and services) of estuaries. The more 'science' orientated paradigms incorporate the development and types of ecotones, the nature of stressed and variable systems (with specific reference to resilience and redundancy), the relationship between generalists and specialists produced by environmental tolerance, the relevance of scale in relation to functioning and connectivity, the sources of production and degree of productivity, the biodiversity-ecosystem functioning and the stress-subsidy debates. The more 'management' targeted paradigms include the development and effects of exogenic unmanaged pressures and endogenic managed pressures, the perception of health and the ability to manage estuaries (related to internal and external influences), and the influence of all of these on the production of ecosystem services and societal benefits.

  16. Estimating flood exceedance probabilities in estuarine regions

    NASA Astrophysics Data System (ADS)

    Westra, Seth; Leonard, Michael

    2016-04-01

    Flood events in estuarine regions can arise from the interaction of extreme rainfall and storm surge. Determining flood level exceedance probabilities in these regions is complicated by the dependence of these processes for extreme events. A comprehensive study of tide and rainfall gauges along the Australian coastline was conducted to determine the dependence of these extremes using a bivariate logistic threshold-excess model. The dependence strength is shown to vary as a function of distance over many hundreds of kilometres indicating that the dependence arises due to synoptic scale meteorological forcings. It is also shown to vary as a function of storm burst duration, time lag between the extreme rainfall and the storm surge event. The dependence estimates are then used with a bivariate design variable method to determine flood risk in estuarine regions for a number of case studies. Aspects of the method demonstrated in the case studies include, the resolution and range of the hydraulic response table, fitting of probability distributions, computational efficiency, uncertainty, potential variation in marginal distributions due to climate change, and application to two dimensional output from hydraulic models. Case studies are located on the Swan River (Western Australia), Nambucca River and Hawkesbury Nepean River (New South Wales).

  17. Impact of estuarine pollution on birds

    USGS Publications Warehouse

    Blus, L.J.; Wiemeyer, Stanley N.; Kerwin, J.A.; Stendell, R.C.; Ohlendorf, H.M.; Stickel, L.F.

    1977-01-01

    Pollution of estuaries affects bird populations indirectly through changes in habitat and food supply. The multi-factor pollution of Chesapeake Bay has resulted in diminution of submerged aquatic plants and consequent change in food habits of the canvasback duck. Although dredge-spoil operations can improve wildlife habitat, they often result in its demise. Pollution of estuaries also affects birds directly, through chemical toxication, which may result in outright mortality or in reproductive impairment. Lead from industrial sources and roadways enters the estuaries and is accumulated in tissues of birds. Lead pellets deposited in estuaries as a result of hunting are consumed by ducks with sufficient frequency .to result m large annual die-offs from lead poisoning. Fish in certain areas, usually near industrial sources, may contain levels of mercury high enough to be hazardous to birds that consume them. Other heavy metals are present in estuarine birds, but their significance is poorly known. Oil exerts lethal or sublethal effects on birds by oiling their feathers, oiling eggs and young by contaminated parents, and by ingestion of oil-contaminated food. Organochlorine chemicals, of both agricultural and industrial origin, travel through the food chains and reach harmful levels in susceptible species of birds in certain estuarine ecosystems. Both outright mortality and reproductive impairment have occurred.

  18. A 150-million-year-old crab larva and its implications for the early rise of brachyuran crabs.

    PubMed

    Haug, Joachim T; Martin, Joel W; Haug, Carolin

    2015-03-09

    True crabs (Brachyura) are the most successful group of decapod crustaceans. This success is most likely coupled to their life history, including two specialised larval forms, zoea and megalopa. The group is comparably young, starting to diversify only about 100 million years ago (mya), with a dramatic increase in species richness beginning approximately 50 mya. Early evolution of crabs is still very incompletely known. Here, we report a fossil crab larva, 150 mya, documented with up-to-date imaging techniques. It is only the second find of any fossil crab larva, but the first complete one, the first megalopa, and the oldest one (other fossil ca. 110 mya). Despite its age, the new fossil possesses a very modern morphology, being indistinguishable from many extant crab larvae. Hence, modern morphologies must have been present significantly earlier than formerly anticipated. We briefly discuss the impact of this find on our understanding of early crab evolution.

  19. Crab Crossing Schemes and Studies for Electron Ion Collider

    SciTech Connect

    S. Ahmed, Y. Derbenev, V. Morozov, A. Castilla, G.A. Krafft, B. Yunn, Y. Zhang, J.R. Delayen

    2011-09-01

    This report shows our progress in crab crossing consideration for future electron-ion collider envisioned at JLab. In this design phase, we are evaluating two crabbing schemes viz., the deflecting and dispersive. The mathematical formulations and lattice design for these schemes are discussed in this paper. Numerical simulations involving particle tracking through a realistic deflecting RF cavity and optics illustrate the desired crab tilt of 25 mrad for 1.35 MV. Evolution of beam propagation are shown which provides the physical insight of the crabbing phenomenon.

  20. Unravelling polar lipids dynamics during embryonic development of two sympatric brachyuran crabs (Carcinus maenas and Necora puber) using lipidomics

    PubMed Central

    Rey, Felisa; Alves, Eliana; Melo, Tânia; Domingues, Pedro; Queiroga, Henrique; Rosa, Rui; Domingues, M. Rosário M.; Calado, Ricardo

    2015-01-01

    Embryogenesis is an important stage of marine invertebrates with bi-phasic life cycles, as it conditions their larval and adult life. Throughout embryogenesis, phospholipids (PL) play a key role as an energy source, as well as constituents of biological membranes. However, the dynamics of PL during embryogenesis in marine invertebrates is still poorly studied. The present work used a lipidomic approach to determine how polar lipid profiles shift during embryogenesis in two sympatric estuarine crabs, Carcinus maenas and Necora puber. The combination of thin layer chromatography, liquid chromatography – mass spectrometry and gas chromatography – mass spectrometry allowed us to achieve an unprecedented resolution on PL classes and molecular species present on newly extruded embryos (stage 1) and those near hatching (stage 3). Embryogenesis proved to be a dynamic process, with four PL classes being recorded in stage 1 embryos (68 molecular species in total) and seven PL classes at stage 3 embryos (98 molecular species in total). The low interspecific difference recorded in the lipidomic profiles of stage 1 embryos appears to indicate the existence of similar maternal investment. The same pattern was recorded for stage 3 embryos revealing a similar catabolism of embryonic resources during incubation for both crab species. PMID:26419891

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

    PubMed

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

    2012-09-01

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

  2. Compact Superconducting Crabbing and Deflecting Cavities

    SciTech Connect

    De Silva, Payagalage Subashini Uddika

    2012-09-01

    Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM{sub 110} cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities.

  3. Pulsating Radio Sources near the Crab Nebula.

    PubMed

    Staelin, D H; Reifenstein, E C

    1968-12-27

    Two new pulsating radio sources, designated NP 0527 and NP 0532, were found near the Crab Nebula and could be coincident with it. Both sources are sporadic, and no periodicities are evident. The pulse dispersions indicate that 1.58 +/- 0.03 and 1.74 +/- 0.02 x 10(20) electrons per square centimeter lie in the direction of NP 0527 and NP 0532, respectively.

  4. Multiband observations of the Crab Nebula

    NASA Astrophysics Data System (ADS)

    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.

  5. Status of the ILC Crab Cavity Development

    SciTech Connect

    Burt, G.; Dexter, A.; Beard, C.; Goudket, P.; McIntosh, P.; Bellantoni, L.; Grimm, T.; Li, Z.; Xiao, L.; /SLAC

    2011-10-20

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

  6. Acute toxicity of current and alternative oil spill chemical dispersants to early life stage blue crabs (Callinectes sapidus).

    PubMed

    Pie, Hannah V; Mitchelmore, Carys L

    2015-06-01

    The aim of this study was to examine the acute toxicity of five oil spill chemical dispersants on the ecologically and economically important coastal and estuarine species, blue crab Callinectes sapidus. Static, non-renewal 48 h acute toxicity tests were performed on stage-II blue crab zoea. The median lethal concentration (LC50) was calculated for each dispersant at 24 h and 48 h using nominal concentrations for each dispersant tested. The 48 h LC50 values from the most to the least toxic ranged from 10.1 mg L(-1) for Dispersit SPC 1000 to 76.5 mg L(-1) for Orca. For all dispersants, the swimming activity and mobility of larvae decreased with increasing dispersant concentration within 24h of exposure and reached relative immobility at concentrations below LC50 values. These results show that the dispersants examined in this study are only slightly toxic after 48 h exposure to the earliest life stage of blue crabs that might likely be exposed to dispersants in the environment, with the exception of Dispersit SPC 1000 that bordered between slightly and moderately toxic. Although the dispersants themselves appear to not cause substantial acute toxicity, sublethal and potentially delayed impacts, such as, reduced mobility or food source availability could indirectly remove larvae from the population and need to be further examined, as do larval responses in standard chronic toxicity tests. Furthermore, dispersants are not released into the environment in isolation and so the impact of dispersed-oil using these dispersant formulations also needs to be investigated to translate into real-world situations.

  7. CMS distributed data analysis with CRAB3

    NASA Astrophysics Data System (ADS)

    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.

  8. CRAB: Distributed analysis tool for CMS

    NASA Astrophysics Data System (ADS)

    Sala, Leonardo; CMS Collaboration

    2012-12-01

    CMS has a distributed computing model, based on a hierarchy of tiered regional computing centers and adopts a data driven model for the end user analysis. This model foresees that jobs are submitted to the analysis resources where data are hosted. The increasing complexity of the whole computing infrastructure makes the simple analysis work flow more and more complicated for the end user. CMS has developed and deployed a dedicated tool named CRAB (CMS Remote Analysis Builder) in order to guarantee the physicists an efficient access to the distributed data whilst hiding the underlying complexity. This tool is used by CMS to enable the running of physics analysis jobs in a transparent manner over data distributed across sites. It factorizes out the interaction with the underlying batch farms, grid infrastructure and CMS data management tools, allowing the user to deal only with a simple and intuitive interface. We present the CRAB architecture, as well as the current status and lessons learnt in deploying this tool for use by the CMS collaboration. We also present the future development of the CRAB system.

  9. CMS distributed data analysis with CRAB3

    SciTech Connect

    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.

    2015-12-23

    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. Furthermore, the new system improves the robustness, scalability and sustainability of the service.Here we provide an overview of the new system, operation, and user support, report on its current status, and identify lessons learned from the commissioning phase and production roll-out.

  10. CMS distributed data analysis with CRAB3

    DOE PAGES

    Mascheroni, M.; Balcas, J.; Belforte, S.; ...

    2015-12-23

    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 andmore » 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. Furthermore, 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.« less

  11. The inner knot of the Crab nebula

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim; Komissarov, Serguei S.; Porth, Oliver

    2016-02-01

    We model the inner knot of the Crab nebula as a synchrotron emission coming from the non-spherical MHD termination shock of relativistic pulsar wind. The post-shock flow is mildly relativistic; as a result the Doppler beaming has a strong impact on the shock appearance. The model can reproduce the knot location, size, elongation, brightness distribution, luminosity and polarization provided the effective magnetization of the section of the pulsar wind producing the knot is low, σ ≤ 1. In the striped wind model, this implies that the striped zone is rather wide, with the magnetic inclination angle of the Crab pulsar ≥45°; this agrees with the previous model-dependent estimate based on the gamma-ray emission of the pulsar. We conclude that the tiny knot is indeed a bright spot on the surface of a quasi-stationary magnetic relativistic shock and that this shock is a site of efficient particle acceleration. On the other hand, the deduced low magnetization of the knot plasma implies that this is an unlikely site for the Crab's gamma-ray flares, if they are related to the fast relativistic magnetic reconnection events.

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

    SciTech Connect

    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

  13. Burrow surveillance in fiddler crabs. II. The sensory cues.

    PubMed

    Hemmi, Jan M; Zeil, J

    2003-11-01

    Using crab-like dummies, we have shown previously that fiddler crabs [Uca vomeris (McNeill)] defend their burrows against intruders in a burrow-centred frame of reference. The crabs respond whenever an intruder approaches to within a certain distance of the burrow entrance, and this distance is independent of the approach direction. We show here that the crabs combine information from the path integration system on the location of their invisible burrow and visual information on the retinal position of an intruder to make this allocentric judgement. Excluding all alternative visual cues, we propose that the crabs employ a small set of matched visual filters to determine the relationship between a crab-like object and the invisible burrow. To account for the constantly varying distance between the crabs and their burrows, the state of the path integrator may select the appropriate one of these retinal 'warning zones'. We have shown before that burrow-owning fiddler crabs are extremely responsive to potential burrow snatchers, which we simulated with crab-like dummies moving across the substratum towards the burrow of residents. The crab's decision to respond to these dummies depends mainly on the spatial arrangement between itself, its burrow and the approaching dummy. The most important factor predicting response probability is the dummy's distance from the crab's burrow: the crabs are more likely to respond the closer the dummy approaches the burrow. The dummy-burrow distance not only determines the overall response probability but also the timing of burrow defence responses (i.e. when the crabs decide to react). Most interestingly, this response distance is independent of the dummy's direction of approach to the burrow. In addition, the crabs respond earlier to a dummy approaching their burrow if they themselves are further away from it, indicating that knowledge of their own distance from the burrow has an influence on their decision to respond. These results

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

    PubMed

    Zotti, Maurizio; Coco, Laura Del; Pascali, Sandra Angelica De; Migoni, Danilo; Vizzini, Salvatrice; Mancinelli, Giorgio; Fanizzi, Francesco Paolo

    2016-02-01

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

  15. Estuarine and coastal challenges in China

    NASA Astrophysics Data System (ADS)

    Chen, Ji-Yu; Chen, Shen-Liang

    2002-06-01

    Estuaries and coasts are conjunctions of four spheres (atmosphere, lithosphere, hydrosphere and biosphere) and important matter and energy convergence/divergence zones, where developed economy, dense population and highly intensive exploitation induce adverse environmental changes and serious destruction of resources, which have great impacts on coastal sustainable development, especially as the highly intensive development in river basins has direct and pronounced effects on estuaries and their adjacent coasts. In the new century, China's estuaries and coast are faced with four main challenges: sharp decrease of sediment discharge into the sea, rapid increase of pollution matter into the sea, loss of coastal wetland, and the impacts of global sea level rise on the coastal lowlands of China. Therefore, it is undoubtedly very important and urgent to carry out studies on estuarine and coastal environmental changes, in order to resolve the issue of national sustainable development, especially that of rational use of coastal zone resources.

  16. Sediment measurement in estuarine and coastal areas

    NASA Technical Reports Server (NTRS)

    Shelley, P. E.

    1976-01-01

    A survey of uses of estuarine and coastal areas is given. Problems associated with these uses are discussed, and data needs for intelligent management of these valuable areas are outlined. Suspended sediment measurements are seen to be one of the greatest needs. To help understand the complexity of the problem, a brief discussion of sediment mechanics is given, including sediment sources, characteristics, and transport. The impact of sediment mechanics on its direct measurement (sampling and analysis) is indicated, along with recommendations for directly obtaining representative data. Indirect measurement of suspended sediment by remote sensors is discussed both theoretically and in the light of some recent experiences. The need for an integrated, multidisciplinary program to solve the problem of quantitatively measuring suspended sediment with remote sensors is stressed, and several important considerations of such a program and benefits to be derived therefrom are briefly addressed.

  17. Numerical noise in ocean and estuarine models

    USGS Publications Warehouse

    Walters, R.; Carey, G.F.

    1984-01-01

    Approximate methods for solving the shallow water equations may lead to solutions exhibiting large fictitious, numerically-induced oscillations. The analysis of the discrete dispersion relation and modal solutions of small wavelengths provides a powerful technique for assessing the sensitivity of alternative numerical schemes to irregular data which may lead to such oscillatory numerical noise. For those schemes where phase speed vanishes at a finite wavenumber or there are multiple roots for wavenumber, oscillation modes can exist which are uncoupled from the dynamics of the problem. The discrete modal analysis approach is used here to identify two classes of spurious oscillation modes associated respectively with the two different asymptotic limits corresponding to estuarine and large scale ocean models. The analysis provides further insight into recent numerical results for models which include large spatial scales and Coriolis acceleration. ?? 1984.

  18. Nitrous oxide production by estuarine epiphyton

    SciTech Connect

    Law, C.S.; Rees, A.P.; Owens, N.J.P. )

    1993-03-01

    Nitrous oxide was produced by denitrifying bacteria in epiphytic communities on the surface of the macroalgae Enteromorpha sp. and Fucus sp. during spring-summer in the Tamar estuary, SW England. Denitrification and N[sub 2]O production exhibited diel variability, in response to photosynthetic oxygen production. Temporal variability in the rate of N[sub 2]O production was observed in Enteromorpha incubations; the variability reflected the heterogeneity of the epiphytic microbial population density. N[sub 2]O production by epiphyton associated with Enteromorpha would enhance the sediment N[sub 2]O flux by 150-500% at maximal algal densities and so increase estuarine N[sub 2]O flux to the atmosphere. 20 refs., 6 figs.

  19. Experimental infections of Orchitophrya stellarum (Scuticociliata) in American blue crabs (Callinectes sapidus) and fiddler crabs (Uca minax).

    PubMed

    Miller, Terrence L; Small, Hamish J; Peemoeller, Bhae-Jin; Gibbs, David A; Shields, Jeffrey D

    2013-11-01

    Outbreaks of an unidentified ciliate have occurred on several occasions in blue crabs from Chesapeake Bay held during winter months in flow-through systems. The parasite was initially thought to be Mesanophrys chesapeakensis, but molecular analysis identified it as Orchitophyra stellarum, a facultative parasite of sea stars (Asteroidea). We investigated the host-parasite association of O. stellarum in the blue crab host. Crabs were inoculated with the ciliate, or they were held in bath exposures after experimentally induced autotomy of limbs in order to determine potential mechanisms for infection. Crabs inoculated with the ciliate, or exposed to it after experimental autotomy, rapidly developed fatal infections. Crabs that were not experimentally injured, but were exposed to the ciliate, rarely developed infections; thus, indicating that the parasite requires a wound or break in the cuticle as a portal of entry. For comparative purposes, fiddler crabs, Uca minax, were inoculated with the ciliate in a dose-titration experiment. Low doses of the ciliate (10 per crab) were sometimes able to establish infections, but high intensity infections developed quickly at doses over 500 ciliates per crab. Chemotaxis studies were initiated to determine if the ciliate preferentially selected blue crab serum (BCS) over other nutrient sources. Cultures grown on medium with BCS or fetal bovine serum showed some conditioning in their selection for different media, but the outcome in choice experiments indicated that the ciliate was attracted to BCS and not seawater. Our findings indicate that O. stellarum is a facultative parasite of blue crabs. It can cause infections in exposed crabs at 10-15°C, but it requires a portal of entry for successful host invasion, and it may find injured hosts using chemotaxis.

  20. 50 CFR 680.6 - Crab economic data report (EDR).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Crab economic data report (EDR). 680.6... ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) SHELLFISH FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA General § 680.6 Crab economic data report (EDR). (a) Requirements. (1) Any owner or leaseholder of...

  1. X-Ray Spectral Evolution of the Crab Pulse

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Pravdo, S. H.; Angelini, L.

    1997-01-01

    The Crab Pulsar was observed with the X-ray detectors on the Rossi X-ray Timing Explorer (RXTE) on May 2, 1996. The large area, high time resolution, extended energy range, and moderate energy resolution of the RXTE instruments provided an unprecedented measurement of the Crab pulsar spectrum as it evolved in phase across the 33 msec pulse.

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

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab Species Code 2 Table 2 to Part 680 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION..., Table 2 Table 2 to Part 680—Crab Species Code Species code Common name Scientific name 900...

  3. 50 CFR Table 4 to Part 680 - Crab Process Codes

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab Process Codes 4 Table 4 to Part 680 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION..., Table 4 Table 4 to Part 680—Crab Process Codes Process code Description 0 Other (specify). 1 Fresh....

  4. 50 CFR Table 6 to Part 680 - Crab Grade Codes

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Crab Grade Codes 6 Table 6 to Part 680 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION..., Table 6 Table 6 to Part 680—Crab Grade Codes Grade/code Description 1 Standard or premium quality...

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

    USGS Publications Warehouse

    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.

  6. 50 CFR 680.21 - Crab harvesting cooperatives.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Crab harvesting cooperatives. 680.21 Section 680.21 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND... IFQ permit issued to the crab harvesting cooperative for the current fishing season. (2) Transfer...

  7. 50 CFR 680.6 - Crab economic data report (EDR).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Crab economic data report (EDR). 680.6... ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) SHELLFISH FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA General § 680.6 Crab economic data report (EDR). (a) Requirements. (1) Any owner or leaseholder of...

  8. Enhanced gamma-ray activity from the Crab nebula

    NASA Astrophysics Data System (ADS)

    Buehler, R.; Ciprini, S.

    2016-01-01

    Preliminary LAT analysis indicates enhanced gamma-ray activity from the Crab nebula. The daily-averaged gamma-ray emission (E > 100 MeV) from the direction of the Crab Nebula has surpassed 4.0 x 10^-6 ph cm^-2 s^-1 five times in the last 12 days.

  9. Crabbed Waist Collisions in DAFNE and Super-B Design

    SciTech Connect

    Raimondi, P.; Alesini, D.; Biagini, M.E.; Biscari, C.; Boni, R.; Boscolo, M.; Bossi, F.; Buonomo, B.; Clozza, A.; Delle Monache, G.O.; Demma, T.; Di Pasquale, E.; Di Pirro, G.; Drago, A.; Gallo, A.; Ghigo, A.; Guiducci, S.; Ligi, C.; Marcellini, F.; Mazzitelli, Giovanni; Milardi, C.; /Frascati /Orsay, LAL /CERN /Rome III U. /Rome U. /Novosibirsk, IYF /KEK, Tsukuba /INFN, Pisa /INFN, Cosenza /SLAC /Frascati

    2011-11-02

    The new idea of increasing the luminosity of a collider with crab waist collisions and first experimental results from the DA{Phi}NE {Phi}-Factory at LNF, Frascati, using this concept are presented. Consequences for the design of future factories will be discussed. An outlook to the performance reach with crab waist collisions is given, with emphasis on future B Factories.

  10. 50 CFR Table 5 to Part 680 - Crab Size Codes

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Crab Size Codes 5 Table 5 to Part 680 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) SHELLFISH FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 680, Table 5 Table 5 to Part 680—Crab...

  11. 50 CFR Table 5 to Part 680 - Crab Size Codes

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Crab Size Codes 5 Table 5 to Part 680 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) SHELLFISH FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 680, Table 5 Table 5 to Part 680—Crab...

  12. Estuarine Macroinvertebrate Pollution Indicator Species in the Virginian Biogeographic Province

    EPA Science Inventory

    Macroinvertebrates are commonly used as biomonitors to detect pollution impacts in estuaries. In this study we identified estuarine benthic invertebrates that could be used to detect presence or absence of pollution in the Virginian Biogeographic Province using available monitor...

  13. 76 FR 2083 - National Estuarine Research Reserve System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-12

    ... National Oceanic and Atmospheric Administration National Estuarine Research Reserve System AGENCY..., National Oceanic and Atmospheric Administration, U.S. Department of Commerce. ACTION: Notice of Public... Management, National Ocean Service, National Oceanic and Atmospheric Administration (NOAA), U.S....

  14. Relating watershed nutrient loads to satellite derived estuarine water quality

    EPA Science Inventory

    Nutrient enhanced phytoplankton production is a cause of degraded estuarine water quality. Yet, relationships between watershed nutrient loads and the spatial and temporal scales of phytoplankton blooms and subsequent water quality impairments remain unquantified for most systems...

  15. Progress and Challenges in Coupled Hydrodynamic-Ecological Estuarine Modeling

    EPA Science Inventory

    Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational po...

  16. Connecting fishery sustainability to estuarine habitats and nutrient loading

    EPA Science Inventory

    The production of several important fishery species depends on critical estuarine habitats, including seagrasses and salt marshes. Relatively simple models can be constructed to relate fishery productivity to the extent and distribution of these habitats by linking fishery-depend...

  17. SPECIES INTERACTIONS BETWEEN ESTUARINE DETRITIVORES: INHIBITION OR FACILITATION?

    EPA Science Inventory

    Native Hawaiian estuarine detritivores; the prawn Macrobrachium grandimanus, and the neritid gastropod Neritina vespertina, were maintained in flow-through microcosms with conditioned leaves from two riparian tree species, Hau (Hibiscus tiliaceus) and guava (Psidium guajava). Th...

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

    USGS Publications Warehouse

    Hart, Kristen M.; Crowder, Larry B.

    2011-01-01

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

  19. Crabs in Labs: The Shore Crab (Carcinus maenas) as Teaching Material.

    ERIC Educational Resources Information Center

    Hogarth, P. J.

    1983-01-01

    The shore crab (Carcinus maenas) is an excellent subject for school study, both in the field and the laboratory. It is easily collected and maintained and can be used for a wide range of investigations. Some background details are given and possible areas of investigation suggested. (Author)

  20. SMALL ANGLE CRAB COMPENSATION FOR LHC IR UPGRADE

    SciTech Connect

    CALAGA,R.; DORDA, U.; OHMI, D.; OIDE, K.; TOMAS, R.; ZIMMERMANN, F.

    2007-06-25

    A small angle (< 1 mrad) crab scheme is an attractive option for the LHC luminosity upgrade to recover the geometric luminosity loss from the finite crossing angle [I]. The luminosity loss increases steeply to unacceptable levels as the IP beta function is reduced below its nominal value (see Fig. 1 in Ref. [2]). The crab compensation in the LHC can be accomplished using only two sets of deflecting RF cavities, placed in collision-free straight sections of the LHC to nullify the effective crossing angles at IPI & IP5. We also explore a 400 MHz superconducting cavity design and discuss the pertinent RF challenges. We present IR optics configurations with low-angle crab crossing, study the beam-beam performance and proton-beam emittance growth in the presence of crab compensation, lattice errors, and crab RF noise sources.

  1. 50 CFR Table 2b to Part 679 - Species Codes: FMP Prohibited Species and CR Crab

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... CR Crab 2b Table 2b to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... CR Crab Species Description Code CR Crab Groundfish PSC CRAB Box Lopholithodes mandtii 900 ✓ Dungeness Cancer magister 910 ✓ King, blue Paralithodes platypus 922 ✓ ✓ King, golden (brown)...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... CR Crab 2b Table 2b to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... CR Crab Species Description Code CR Crab Groundfish PSC CRAB Box Lopholithodes mandtii 900 ✓ Dungeness Cancer magister 910 ✓ King, blue Paralithodes platypus 922 ✓ ✓ King, golden (brown)...

  3. 50 CFR Table 2b to Part 679 - Species Codes: FMP Prohibited Species and CR Crab

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CR Crab 2b Table 2b to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... CR Crab Species Description Code CR Crab Groundfish PSC CRAB Box Lopholithodes mandtii 900 ✓ Dungeness Cancer magister 910 ✓ King, blue Paralithodes platypus 922 ✓ ✓ King, golden (brown)...

  4. 50 CFR Table 2b to Part 679 - Species Codes: FMP Prohibited Species and CR Crab

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CR Crab 2b Table 2b to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... CR Crab Species Description Code CR Crab Groundfish PSC CRAB Box Lopholithodes mandtii 900 ✓ Dungeness Cancer magister 910 ✓ King, blue Paralithodes platypus 922 ✓ ✓ King, golden (brown)...

  5. 50 CFR Table 2b to Part 679 - Species Codes: FMP Prohibited Species and CR Crab

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CR Crab 2b Table 2b to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... CR Crab Species Description Code CR Crab Groundfish PSC CRAB Box Lopholithodes mandtii 900 ✓ Dungeness Cancer magister 910 ✓ King, blue Paralithodes platypus 922 ✓ ✓ King, golden (brown)...

  6. Isolation and Characterization of Listeria monocytogenes from Blue Crab Meat (Callinectus sapidus) and Blue Crab Processing Plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Listeria monocytogenes is a Gram positive, intracellular food borne pathogen which causes a severe disease called listeriosis in high risk groups. However, there is limited information about the prevalence and sources of L. monocytogenes in blue crab and blue crab processing plants in Maryland. The...

  7. Chitin extraction from crab shells by Bacillus bacteria. Biological activities of fermented crab supernatants.

    PubMed

    Hajji, Sawssen; Ghorbel-Bellaaj, Olfa; Younes, Islem; Jellouli, Kemel; Nasri, Moncef

    2015-08-01

    Crab shells waste were fermented using six protease-producing Bacillus species (Bacillus subtilis A26, Bacillus mojavensis A21, Bacillus pumilus A1, Bacillus amyloliquefaciens An6, Bacillus licheniformis NH1 and Bacillus cereus BG1) for the production of chitin and fermented-crab supernatants (FCSs). In medium containing only crab shells, the highest demineralization DM was obtained with B. licheniformis NH1 (83±0.5%) and B. pumilus A1 (80±0.6%), while the highest deproteinization (DP) was achieved with A1 (94±1%) followed by NH1 (90±1.5%) strains. Cultures conducted in medium containing crab shells waste supplemented with 5% (w/v) glucose, were found to remarkably promote demineralization efficiency, and enhance slightly deproteinization rates. FTIR spectra of chitins showed the characteristics bands of α-chitin. FCSs showed varying degrees of antioxidant activities which were in a dose-dependent manner (p<0.01). In fact, FCS produced by B. amyloliquefaciens An6 exhibited the highest DPPH free radical-scavenging activity (92% at 4 mg/ml), while the lowest hydroxyl radical-scavenging activity (60% at 4 mg/ml) was obtained with B. subtilis A26 hydrolysates. However, the highest reducing power (OD700nm=2 at 0.5 mg/ml) was obtained by B.amyloliquefaciens An6 hydrolysates. These results suggest that crab hydrolysates are good sources of natural antioxidants. Further, FCSs were found to exhibit antibacterial activity against Gram-positive and Gram-negative bacteria.

  8. VARIATIONS IN THE SPECTRAL PROPERTIES OF FRESHWATER AND ESTUARINE CDOM CAUSED BY PARTITIONING ONTO RIVER AND ESTUARINE SEDIMENTS

    EPA Science Inventory

    The optical properties and geochemical cycling of chromophoric dissolved organic matter (CDOM) are altered by its sorption to freshwater and estuarine sediments. Measured partition coefficients (Kp) of Satilla River (Georgia) and Cape Fear River estuary (North Carolina) CDOM ran...

  9. Switching skeletons: hydrostatic support in molting crabs

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  10. Effects of pesticides on crab cheliped regeneration

    SciTech Connect

    Costlow, J.D. Jr.

    1993-01-01

    The mud crab cheliped regeneration bioassay has proven to be a sensitive and reliable bioassay in studies of the potential sublethal effects of pesticides, including teratogenesis, spontaneous autotomy, and duration of the various stages of development. The assay has also been demonstated to be a useful indication of mortality associated with the impact of these chemicals of anthropogenic origin during the megalopal and early postlarval stages of development. Four pesticides were tested here using the cheliped regeneration bioassay technique. Although carbofuran is approximately 5--6 times more toxic than methomyl, both compounds yield very similar results in terms of sublethal effects.

  11. Element Masses in the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Sibley, Adam R.; Katz, Andrea M.; Satterfield, Timothy J.; Vanderveer, Steven J.; MacAlpine, Gordon M.

    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] λ7378, along with combined photoionization models and analytic computations, a nickel abundance distribution was mapped and a nebular stable nickel mass estimate was derived.

  12. Habitat Suitability Index Models: Red king crab

    USGS Publications Warehouse

    Jewett, Stephen C.; Onuf, Christopher P.

    1988-01-01

    A review and synthesis of existing information were used to develop a Habitat Suitability Index (HSI) model for evaluating habitat of different life stages of red king crab (Paralithodes camtschatica). A model consolidates habitat use information into a framework appropriate for field application, and is scaled to produce an index between 0.0 (unsuitable habitat) and 1.0 (optimum habitat) in Alaskan coastal waters, especially in the Gulf of Alaska and the southeastern Bering Sea. HSI models are designed to be used with Habitat Evaluation Procedures previously developed by the U.S. Fish and Wildlife Service.

  13. Abundance, Health and Status of Sand Crabs at Ocean Beach, San Francisco: Comparisons From two Summers, 2003 and 2004

    NASA Astrophysics Data System (ADS)

    Conrad-Saydah, A.; MacCormack, D.; Velarde, M.; Masters, D.; Walton, M.

    2004-12-01

    Interns from the California Academy of Sciences in San Francisco monitored Pacific mole crabs, Emerita analoga, commonly known as sand crabs, at Ocean Beach, San Francisco for the second consecutive summer. Comparisons from two data sets revealed trends in crab abundance, size and location. Changes in abundance and location may have been related to water temperature and predation. Dissections of random crabs from all gender classes allowed inspection of parasitism on the crabs. The dissections revealed increased numbers of parasites in larger crabs (especially females with eggs) and in crabs collected later in the summer season. Crab parasitism may be connected to population changes of species predating the sand crabs.

  14. Symbiotic crabs maintain coral health by clearing sediments

    NASA Astrophysics Data System (ADS)

    Stewart, Hannah L.; Holbrook, Sally J.; Schmitt, Russell J.; Brooks, Andrew J.

    2006-11-01

    Stony corals are the foundation of coral reef ecosystems and form associations with other reef species. Many of these associations may be ecologically important and play a role in maintaining the health and diversity of reef systems, rendering it critical to understand the influence of symbiotic organisms in mediating responses to perturbation. This study demonstrates the importance of an association with trapeziid crabs in reducing adverse effects of sediments deposited on corals. In a field experiment, mortality rates of two species of branching corals were significantly lowered by the presence of crabs. All outplanted corals with crabs survived whereas 45-80% of corals without crabs died within a month. For surviving corals that lacked crabs, growth was slower and tissue bleaching and sediment load were higher. Laboratory experiments revealed that corals with crabs shed substantially more of the sediments deposited on coral surfaces, but also that crabs were most effective at removing grain sizes that were most damaging to coral tissues. The mechanism underlying this symbiotic relationship has not been recognized previously, and its role in maintaining coral health is likely to become even more critical as reefs worldwide experience increasing sedimentation.

  15. Mangrove crabs as ecosystem engineers; with emphasis on sediment processes

    NASA Astrophysics Data System (ADS)

    Kristensen, Erik

    2008-02-01

    The benthic fauna in mangrove forests is usually dominated by burrowing sesarmid (Grapsidae) and fiddler crabs (Ocypodidae). They are herbivores that retain, bury, macerate and ingest litter and microalgal mats. Most species within these two groups actively dig and maintain burrows in the sediment as a refuge from predation and environmental extremes. Based on the current knowledge on the biology and ecology of these crabs, it seems obvious that their activities have considerable impact on ecosystem functioning. However, no convincing conceptual framework has yet been defined into which the role of these crabs can be identified and characterized. The attributes by which these abundant animals affect the microbial and biogeochemical functional diversity fit well into the concept of ecosystem engineering. The conceptualization of mangrove benthic communities within this framework is distinguished and documented by examples provided from the most recent literature on mangrove ecosystem functioning. It appears that the features and processes driving the engineering effects on distribution and activity of associated organisms operate differently for sesarmid and fiddler crabs. The most obvious and well-documented difference between engineering effects of the two types of crab seems to be associated with foraging. More attention must be devoted in the future to elucidate engineering aspects related to crab burrows in mangrove environments. Particularly comparative work on the burrow-dwelling life styles of the two types of crab is needed.

  16. OBSERVATIONS OF THE CRAB NEBULA'S ASYMMETRICAL DEVELOPMENT

    SciTech Connect

    Loll, A. M.; Desch, S. J.; Scowen, P. A.; Foy, J. P.

    2013-03-10

    We present the first Hubble Space Telescope Wide Field Planetary Camera-2 imaging survey of the entire Crab Nebula, in the filters F502N ([O III] emission), F673N ([S II]), F631N ([O I]), and F547M (continuum). We use our mosaics to characterize the pulsar wind nebula (PWN) and its three-dimensional structure, the ionizational structure in the filaments forming at its periphery, the speed of the shock driven by the PWN into surrounding ejecta (by inferring the cooling rates behind the shock), and the morphology and ionizational structure of the Rayleigh-Taylor (R-T) fingers. We quantify a number of asymmetries between the northwest (NW) and southeast (SE) quadrants of the Crab Nebula. The lack of observed filaments in the NW, and our observations of the spatial extent of [O III] emission lead us to conclude that cooling rates are slower, and therefore the shock speeds are greater, in the NW quadrant of the nebula, compared with the SE. We conclude that R-T fingers are longer, more ionizationally stratified, and apparently more massive in the NW than in the SE, and the R-T instability appears more fully developed in the NW.

  17. Territorial battles between fiddler crab species

    PubMed Central

    Backwell, P. R. Y.

    2017-01-01

    Many species worldwide are impacted by habitat loss. This may result in increased competition both within species and between species. Many studies have demonstrated that when two previously non-overlapping species are forced to compete over a resource, one species is likely to become dominant over the other. This study explores the impact a larger species of fiddler crab (Tabuca elegans—previously known as Uca elegans) has when invading an area previously used solely by a smaller species (Austruca mjoebergi—previously known as Uca mjoebergi). Here we show that, while there are some detrimental effects of living next to a heterospecific, they are relatively minor. New heterospecific neighbours fight more regularly with resident crabs, but each fight is no longer or more escalated than those between the resident and a new conspecific male. The residents are not specifically targeted by intruding heterospecifics, thus, given the large advantage of having a heterospecific neighbour in terms of lowered competition for females, the overall impact of species mixing is probably not as negative as might have been predicted. PMID:28280560

  18. Territorial battles between fiddler crab species.

    PubMed

    Clark, H L; Backwell, P R Y

    2017-01-01

    Many species worldwide are impacted by habitat loss. This may result in increased competition both within species and between species. Many studies have demonstrated that when two previously non-overlapping species are forced to compete over a resource, one species is likely to become dominant over the other. This study explores the impact a larger species of fiddler crab (Tabuca elegans-previously known as Uca elegans) has when invading an area previously used solely by a smaller species (Austruca mjoebergi-previously known as Uca mjoebergi). Here we show that, while there are some detrimental effects of living next to a heterospecific, they are relatively minor. New heterospecific neighbours fight more regularly with resident crabs, but each fight is no longer or more escalated than those between the resident and a new conspecific male. The residents are not specifically targeted by intruding heterospecifics, thus, given the large advantage of having a heterospecific neighbour in terms of lowered competition for females, the overall impact of species mixing is probably not as negative as might have been predicted.

  19. Melatonin and locomotor activity in the fiddler crab Uca pugilator.

    PubMed

    Tilden, Andrea R; Shanahan, J Kearney; Khilji, Zahra S; Owen, Jeffrey G; Sterio, Thomas W; Thurston, Kristy T

    2003-05-01

    The influence of melatonin on locomotor activity levels was measured in the fiddler crab Uca pugilator. First, activity in untreated, laboratory-acclimated crabs was measured over 48 hours in a 12L:12D photoperiod; this study showed a nocturnal increase in activity. In eyestalk-ablated crabs, overall activity was significantly reduced, and no significant activity pattern occurred. Next, crabs were injected with melatonin or saline (controls) at various times during the 12L:12D photoperiod (0900h, 1200h, and twice at 2100h; each trial was separated by 3-4 days) and monitored for 3 hr post-injection. Control crabs had low activity during early photophase, high at mid-photophase, increasing activity during the first scotophase trial, and decreasing activity during the second scotophase trial. Melatonin had no significant influence on activity when injected during the early-photophase activity trough or early-scotophase activity decline, but significantly increased activity when injected during the mid-photophase activity peak and early-scotophase activity incline. Next, crabs were injected during an early scotophase activity trough and monitored throughout the twelve-hour scotophase. Melatonin did not increase activity until the mid-scotophase activity increase, approximately 6 hours later, showing that the pharmacological dosage persisted in the crabs' systems and had later effects during the incline and peak of activity but not the trough. Eyestalk-ablated crabs were injected with melatonin or saline during early photo- and scotophase. Melatonin significantly increased activity in the photophase but not the scotophase trial, indicating that the responsiveness to melatonin continues following eyestalk removal, but the timing may not match that of intact crabs. Melatonin may be involved in the transmission of environmental timing information from the eyestalks to locomotor centers in U. pugilator.

  20. Estuarine resources use by juvenile Flagfin mojarra ( Eucinostomus melanopterus) in an inverse tropical estuary (Sine Saloum, Senegal)

    NASA Astrophysics Data System (ADS)

    Gning, Ndombour; Le Loc'h, François; Thiaw, Omar T.; Aliaume, Catherine; Vidy, Guy

    2010-03-01

    The Flagfin mojarra, Eucinostomus melanopterus, is a marine spawner whose young individuals are common in the Sine Saloum inverse estuary (Senegal). The species offers the opportunity to study both the use of the estuarine nursery resources and the impact of the particular environment of the inverse estuary on these resources. This will lead to a better understanding of the functioning of the nursery. We investigated the resources used by juvenile Flagfin mojarra by coupling stomach contents and stable isotopes methods. Young Flagfin mojarra feed on a wide range of invertebrates. Diet changed from copepods in the smallest size class (10-40 mm), to a range of invertebrates including amphipods, insect larvae, polychaetes and mollusc in the medium size class (up to 60 mm) and mainly polychaetes for individuals >60 mm in size. In mangrove habitats with moderate salinity, the diet was dominated by polychaetes and decapod larvae (crabs) whereas in habitats with higher salinity, diet was dominated by amphipods. In very hypersaline areas with scarce mangroves, diet comprised benthic copepods, chironomid larvae and ostracods. This agreed with a clear change in δ13C measured in fish sampled at downstream or upstream sites. Comparison with signatures of primary producers suggested that the local food web exploited by young Flagfin mojarra is mainly based on phytoplankton in the downstream mangrove area, and mainly on benthic microalgae in the upstream hypersaline area. As in many studies considering the food webs in mangrove, mangrove was not identified as a major contributor to the food web exploited by E. melanopterus. This needs further investigation particularly because the exportation of estuarine materials to the sea is limited in an inverse estuary.

  1. Biogeochemical studies of technetium in marine and estuarine ecosystems. Progress report, 1 July 1979-30 June 1980

    SciTech Connect

    Beasley, T. M.

    1980-01-01

    Progress is reported in research dealing with the biogeochemical behavior of technetium in marine and estuarine ecosystems. Studies were planned to elaborate the biokinetic behavior of Tc as TcO/sub 4//sup -/ in selected marine and estuarine organisms and to determine the affinity of TcO/sub 4//sup -/ for different marine sediments under oxygenated conditions. It is concluded that concentration factors for TcO/sub 4//sup -/ in bivalve molluscs (oysters and mussels) do not exceed 2 when calculated for whole animals and when uptake is directly from water. Direct uptake from water by limpets (archeogastropod) are very much lower than have been reported for red abalone (archeogastropod). Whole body concentration factors for TcO/sub 4//sup -/ in the plaice, Pleuronectes platessa, where uptake is directly from labeled seawater, do not exceed 10 at equilibrium. Both the lobster, Homarus gammaris and the polychaete, Nereis diversicolor appear to concentrate Tc efficiently from water labelled intially with TcO/sub 4//sup -/. Both plaice and rays (Raja clavata) fed /sup 95m/Tc labeled Nereis show an initial rapid loss of the isotope for approximately five days. Thereafter, loss is much reduced. Shrimp (Palaemon elegans), Cragnon sp.) and Crab (Cancer pagurus) show concentration factors similar to plaice (C.F. is less than 10). Isopods, however, have concentration factors of only 3 following four weeks exposure to labeled seawater. Uptake of TcO/sub 4//sup -/ by phytoplankton is extremely low, which precludes experiments in which TcO/sub 4//sup -/ labeled phytoplankton can be fed to either bivalve molluscs or microzooplankton. Sediment distribution coefficients for TcO/sub 4//sup -/ are essentially zero and are independent of sediment type in well oxygenated seawater. Experiments to date have shown that it is not possible to make generalizations concerning the bioavailability of TcO/sub 4//sup -/ to marine organisms.

  2. Composition of estuarine colloidal material: organic components

    USGS Publications Warehouse

    Sigleo, A.C.; Hoering, T.C.; Helz, G.R.

    1982-01-01

    Colloidal material in the size range 1.2 nm to 0.4 ??m was isolated by ultrafiltration from Chesapeake Bay and Patuxent River waters (U.S.A.). Temperature controlled, stepwise pyrolysis of the freeze-dried material, followed by gas chromatographic-mass spectrometric analyses of the volatile products indicates that the primary organic components of this polymer are carbohydrates and peptides. The major pyrolysis products at the 450??C step are acetic acid, furaldehydes, furoic acid, furanmethanol, diones and lactones characteristic of carbohydrate thermal decomposition. Pyrroles, pyridines, amides and indole (protein derivatives) become more prevalent and dominate the product yield at the 600??C pyrolysis step. Olefins and saturated hydrocarbons, originating from fatty acids, are present only in minor amounts. These results are consistent with the composition of Chesapeake phytoplankton (approximately 50% protein, 30% carbohydrate, 10% lipid and 10% nucleotides by dry weight). The pyrolysis of a cultured phytoplankton and natural particulate samples produced similar oxygen and nitrogencontaining compounds, although the proportions of some components differ relative to the colloidal fraction. There were no lignin derivatives indicative of terrestrial plant detritus in any of these samples. The data suggest that aquatic microorganisms, rather than terrestrial plants, are the dominant source of colloidal organic material in these river and estuarine surface waters. ?? 1982.

  3. Ecotoxicology of bromoacetic acid on estuarine phytoplankton.

    PubMed

    Gordon, Ana R; Richardson, Tammi L; Pinckney, James L

    2015-11-01

    Bromoacetic acid is formed when effluent containing chlorine residuals react with humics in natural waters containing bromide. The objective of this research was to quantify the effects of bromoacetic acid on estuarine phytoplankton as a proxy for ecosystem productivity. Bioassays were used to measure the EC50 for growth in cultured species and natural marine communities. Growth inhibition was estimated by changes in chlorophyll a concentrations measured by fluorometry and HPLC. The EC50s for cultured Thalassiosira pseudonana were 194 mg L(-1), 240 mg L(-1) for Dunaliella tertiolecta and 209 mg L(-1) for Rhodomonas salina. Natural phytoplankton communities were more sensitive to contamination with an EC50 of 80 mg L(-1). Discriminant analysis suggested that bromoacetic acid additions cause an alteration of phytoplankton community structure with implications for higher trophic levels. A two-fold EC50 decrease in mixed natural phytoplankton populations affirms the importance of field confirmation for establishing water quality criteria.

  4. Passive acoustic threat detection in estuarine environments

    NASA Astrophysics Data System (ADS)

    Borowski, Brian; Sutin, Alexander; Roh, Heui-Seol; Bunin, Barry

    2008-04-01

    The Maritime Security Laboratory (MSL) at Stevens Institute of Technology supports research in a range of areas relevant to harbor security, including passive acoustic detection of underwater threats. The difficulties in using passive detection in an urban estuarine environment include intensive and highly irregular ambient noise and the complexity of sound propagation in shallow water. MSL conducted a set of tests in the Hudson River near Manhattan in order to measure the main parameters defining the detection distance of a threat: source level of a scuba diver, transmission loss of acoustic signals, and ambient noise. The source level of the diver was measured by comparing the diver's sound with a reference signal from a calibrated emitter placed on his path. Transmission loss was measured by comparing noise levels of passing ships at various points along their routes, where their distance from the hydrophone was calculated with the help of cameras and custom software. The ambient noise in the Hudson River was recorded under varying environmental conditions and amounts of water traffic. The passive sonar equation was then applied to estimate the range of detection. Estimations were done for a subset of the recorded noise levels, and we demonstrated how variations in the noise level, attenuation, and the diver's source level influence the effective range of detection. Finally, we provided analytic estimates of how an array improves upon the detection distance calculated by a single hydrophone.

  5. Estuarine ecology of phenanthrene-degrading bacteria

    NASA Astrophysics Data System (ADS)

    Guerin, William F.; Jones, Galen E.

    1989-08-01

    Phenanthrene degrading bacteria were ubiquitously distributed in waters and sediments of the Great Bay Estuary, NH, as determined using a 14C-phenanthrene mineralization assay. Similar activities were observed in water samples collected in March and June when these were incubated at 18 °C even though ambient water temperatures were 1-4 °C and 10-22 °C, respectively. This observation indicated the constant presence of a mesophilic phenanthrene-degrading bacterial population in the estuary. Among water samples, the highest biodegradation activities were associated with samples collected downstream from a dredging operation which introduced high concentrations of coal tar PAH (polycyclic aromatic hydrocarbons) into the Cocheco River, and in areas receiving PAH from pleasure and commercial boating activities. Mid-estuarine maxima in biodegradation activity during both sampling trips suggested adaptation of the microbial flora to the salinities prevailing in the low turnover, high residence time portion of the Estuary at the time of sampling. Despite the hydrophobicity of phenanthrene, no correlation between biodegradation rates and particulate matter concentrations were observed. Similarly, concentrations of nutrients and dissolved and particulate organic matter correlated poorly with biodegradation rates. Better agreements between 14C-phenanthrene mineralization potentials and plate counts on a phenanthrene/toluene agar (PTA) medium were observed. Phenanthrene biodegradative activities and numbers of culturable bacteria growing on PTA were governed by the degree of previous exposure to PAH.

  6. CEPC partial double ring scheme and crab-waist parameters

    NASA Astrophysics Data System (ADS)

    Wang, Dou; Gao, Jie; Su, Feng; Zhang, Yuan; Zhai, Jiyuan; Wang, Yiwei; Bai, Sha; Geng, Huiping; Bian, Tianjian; Cui, Xiaohao; Wang, Na; Duan, Zhe; Guo, Yuanyuan; Qin, Qing

    2016-11-01

    In order to avoid the pretzel orbit, CEPC is proposed to use partial double ring scheme in CDR. In this paper, a general method of how to make an consistent machine parameter design of CEPC with crab-waist by using analytical expression of maximum beam-beam tune shift and beamstrahlung beam lifetime started from given IP vertical beta, beam power and other technical limitations were developed. FFS with crab sextupoles will be developed and the arc lattice will be redesigned to acheive the lower emittance for crab-waist scheme.

  7. Classification for Estuarine Ecosystems: A Review and Comparison of Selected Classification Schemes

    EPA Science Inventory

    Estuarine scientists have devoted considerable effort to classifying coastal, estuarine and marine environments and their watersheds, for a variety of purposes. These classifications group systems with similarities – most often in physical and hydrodynamic properties – in order ...

  8. Influence of organic carbon on estuarine benthic infauna of the US west coast

    EPA Science Inventory

    Total organic carbon (TOC) is often used as an indicator of eutrophication in estuarine environments. However, the determination of biologically relevant sediment TOC criteria to indicate estuarine condition is complicated by the relationship between TOC and grain size. Both va...

  9. Influence of organic carbon on estuarine benthic infauna of the US west coast - March 3, 2011

    EPA Science Inventory

    Total organic carbon (TOC) is often used as an indicator of eutrophication in estuarine environments. However, the determination of biologically relevant sediment TOC criteria to indicate estuarine condition is complicated by the relationship between TOC and grain size. Both va...

  10. 75 FR 69399 - Evaluation of State Coastal Management Programs and National Estuarine Research Reserves

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-12

    ..., subpart E and part 923, subpart L. Evaluation of a National Estuarine Research Reserve requires findings...:30 p.m. at the Rookery Bay National Estuarine Research Reserve Environmental Learning Center,...

  11. Human mediated transport determines the non-native distribution of a dispersal limited estuarine invertebrate

    EPA Science Inventory

    Sessile invertebrates are common invaders of estuarine ecosystems. To expand their non-native ranges, these invasive taxa must contend with the geographically and ecologically discontinuous nature of estuarine habitats, in many cases without the benefit of highly dispersed larval...

  12. A new genus and two new species of Peltogastridae (Crustacea: Cirripedia: Rhizocephala) parasitizing hermit crabs from Okinawa Island (Ryukyu Archipelago, Japan), and their DNA-barcodes.

    PubMed

    Yoshida, Ryuta; Osawa, Masayuki; Hirose, Mamiko; Hirose, Euichi

    2011-11-01

    A new genus and two new species of Peltogastridae, Peltogaster postica sp. nov. and Ommatogaster nana gen. et sp. nov., are described from Okinawa Island, Ryukyu Islands, southwestern Japan. The two new rhizocephalans were found to be parasitic on the estuarine hermit crabs, Pagurus minutus Hess, 1865 and Diogenes leptocerus Forest, 1956, respectively. Peltogaster postica sp. nov. is allied to P. curvata Kossmann, 1874, P. paguri Rathke, 1842 , and P. reticulata Shiino, 1943 , but is distinguished by its relative length and internal and external structures of the mature externa. Ommatogaster gen. nov. is established for the present new species O. nana based on the morphologies of the visceral mass of the externa and the presence of a nauplius eye in the larvae. Partial COI sequences were obtained from the two new species and one known species, Dipterosaccus indicus Van Kampen and Boschma, 1925, to test the possible usefulness of the sequences as tags for species identification.

  13. Comparison of automated BAX polymerase chain reaction and standard culture methods for detection of Listeria monocyogenes in blue crab meat (Callinectus sapidus) and blue crab processing plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study compared the BAX Polymerase Chain Reaction method (BAX PCR) with the Standard Culture Method (SCM) for detection of L. monocytogenes in blue crab meat and crab processing plants. The aim of this study was to address this data gap. Raw crabs, finished products and environmental sponge samp...

  14. Distributions of key exposure factors controlling the uptake of xenobiotic chemicals in an estuarine food web

    SciTech Connect

    Iannuzzi, T.J.; Harrington, N.W.; Shear, N.M.; Curry, C.L.; Carlson-Lynch, H.; Henning, M.H.; Su, S.H.; Rabbe, D.E.

    1996-11-01

    A critical evaluation of literature on the behavior, physiology, and ecology of common estuarine organisms was conducted in an attempt to develop probabilistic distributions for those variables that influence the uptake of xenobiotic chemicals from sediments, water, and food sources. The ranges, central tendencies, and distributions of several key parameter values were identified for dominant organisms from various trophic levels, including the polychaete Nereis virens, mummichog (Fundulus heteroclitus), blue crab (Callinectes sapidus), and striped bass (Morone saxatilis). The exposure factors of interest included ingestion rate for various food sources, growth rate, respiration rate, excretion rate, body weight, wet/dry weight ratio, lipid content, chemical assimilation efficiency, and food assimilation efficiency. These exposure factors are critical to the execution of mechanistic food web models, which, when properly calibrated, can be used to estimate tissue concentrations of nonionic chemicals in aquatic organisms based on knowledge of the bioenergetics and feeding interactions within a food web and the sediment and water concentrations of chemicals. In this article the authors describe the use of distributions for various exposure factors in the context of a mechanistic bioaccumulation model that is amenable to probabilistic analyses for multiple organisms within a food web. A case study is provided which compares the estimated versus measured concentrations of five polychlorinated biphenyl (PCB) congeners in a representative food web from the tidal portion of the Passaic River, New Jersey, USA. The results suggest that the model is accurate within an order of magnitude or less in estimating the bioaccumulation of PCBs in this food web without calibration. The results of a model sensitivity analysis suggest that the input parameters which most influence the output of the model are both chemical and organism specific.

  15. Influence of the invasive Asian clam Corbicula fluminea (Bivalvia: Corbiculidae) on estuarine epibenthic assemblages

    NASA Astrophysics Data System (ADS)

    Ilarri, M. I.; Souza, A. T.; Antunes, C.; Guilhermino, L.; Sousa, R.

    2014-04-01

    One of the most widespread invasive alien species (IAS) in aquatic ecosystems is the Asian clam Corbicula fluminea. Several studies have shown that C. fluminea can cause large-scale changes in macrozoobenthic assemblages; however, very few attempted to investigate the effects of this IAS on mobile epibenthic species, such as fishes and crustaceans. In this context, the influence of C. fluminea on epibenthic species was investigated during one year by comparing the associated epibenthic fauna in three nearby sites of the Minho estuary (NW of the Iberian Peninsula), wherein the abiotic conditions are similar but the density of the Asian clam is highly different. From a total of 13 species, six were significantly influenced by C. fluminea; five responded positively, namely the brown shrimp Crangon crangon, the European eel Anguilla anguilla, the common goby Pomatoschistus microps, the brown trout Salmo trutta fario and the great pipefish Syngnathus acus, whereas the shore crab Carcinus maenas was negatively influenced. However, stomach contents analysis revealed that fish and crustacean species do not feed on C. fluminea, suggesting that this IAS is still not a large component of the diet of higher trophic levels in this estuarine ecosystem. Our results suggest that the structure provided by C. fluminea shells is likely to be one of the main factors responsible for the differences observed. C. fluminea physical structure seems to influence the epibenthic associated fauna, when found in densities higher than 1000 ind./m2, with sedentary small-bodied crustaceans and fishes being mainly attracted by the increasing in habitat complexity and consequent enhancement of heterogeneity and shelter availability.

  16. Crustaceans from a tropical estuarine sand-mud flat, Pacific, Costa Rica, (1984-1988) revisited.

    PubMed

    Vargas-Zamora, José A; Sibaja-Cordero, Jeffrey A; Vargas-Castillo, Rita

    2012-12-01

    The availability of data sets for time periods of more than a year is scarce for tropical environments. Advances in hardware and software speed-up the re-analysis of old data sets and facilitates the description of population oscillations. Using recent taxonomic literature and software we have updated and re-analized the information on crustacean diversity and population fluctuations from a set of cores collected at a mud-sand flat in the mid upper Gulf of Nicoya estuary, Pacific coast of Costa Rica (1984-1988). A total of 112 morphological species of macroinvertebrates was found, of which 29 were crustaceans. Taxonomic problems, maily with the peracarids, prevented the identification of a group of species. The abundance patterns of the crab Pinnixa valerii, the ostracod Cyprideis pacifica, and the cumacean Coricuma nicoyensis were analized with the Generalized Additive Models of the free software R. The models evidenced a variety of population oscillations during the sampling period. These oscillations probably included perturbations induced by external factors, like the strong red tide events of 1985. In additon, early on 1984 the populations might have been at an altered state due to the inpact of El Niño 1982-83. Thus, the oscillations observed during the study period departed from the expected seasonality (dry vs rainy) pattern and are thus considered atypical for this tropical estuarine tidal-flat. Crustacean diversity and population peaks were within the range of examples found in worldwide literature. However, abundances of the cumacean C. nicoyensis, an endemic species, are the highest reported for a tropical estuary. Comparative data from tropical tidal flat crustaceans continues to be scarce. Crustaceans (total vs groups) had population changes in response to the deployment of predator exclusion cages during the dry and rainy seasons of 1985. Temporal and spatial patchiness characterized the abundances of P. valeri, C. pacifica and C. nicoyenis.

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

    PubMed

    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.

  18. CLIC Crab Cavity Design Optimisation for Maximum Luminosity

    SciTech Connect

    Dexter, A.C.; Burt, G.; Ambattu, P.K.; Dolgashev, V.; Jones, R.; /Manchester U.

    2012-04-25

    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.

  19. Domoic acid excretion in dungeness crabs, razor clams and mussels.

    PubMed

    Schultz, Irvin R; Skillman, Ann; Woodruff, Dana

    2008-07-01

    Domoic acid (DA) is a neurotoxic amino acid produced by several marine algal species of the Pseudo-nitzschia (PN) genus. We studied the elimination of DA from hemolymph after intravascular (IV) injection in razor clams (Siliqua patula), mussels (Mytilus edulis) and Dungeness crabs (Cancer magister). Crabs were also injected with two other organic acids, dichloroacetic acid (DCAA) and kainic acid (KA). For IV dosing, hemolymph was repetitively sampled and DA concentrations measured by HPLC-UV. Toxicokinetic analysis of DA in crabs suggested most of the injected dose remained within hemolymph compartment with little extravascular distribution. This observation is in sharp contrast to results obtained from clams and mussels which exhibited similarly large apparent volumes of distribution despite large differences in overall clearance. These findings suggest fundamentally different storage and elimination processes are occurring for DA between bivalves and crabs.

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

    SciTech Connect

    Wu, Q.

    2015-05-03

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

  1. EVOLUTION OF THE CRAB NEBULA IN A LOW ENERGY SUPERNOVA

    SciTech Connect

    Yang, Haifeng; Chevalier, Roger A. E-mail: rac5x@virginia.edu

    2015-06-20

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼10{sup 50} erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

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

    PubMed

    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.

  3. Evolution of the Crab Nebula in a Low Energy Supernova

    NASA Astrophysics Data System (ADS)

    Yang, Haifeng; Chevalier, Roger A.

    2015-06-01

    The nature of the supernova leading to the Crab Nebula has long been controversial because of the low energy that is present in the observed nebula. One possibility is that there is significant energy in extended fast material around the Crab but searches for such material have not led to detections. An electron capture supernova model can plausibly account for the low energy and the observed abundances in the Crab. Here, we examine the evolution of the Crab pulsar wind nebula inside a freely expanding supernova and find that the observed properties are most consistent with a low energy event. Both the velocity and radius of the shell material, and the amount of gas swept up by the pulsar wind point to a low explosion energy (∼1050 erg). We do not favor a model in which circumstellar interaction powers the supernova luminosity near maximum light because the required mass would limit the freely expanding ejecta.

  4. The Crab Nebula: A Flickering X-ray Candle

    NASA Video Gallery

    The Crab Nebula, created by a supernova seen nearly a thousand years ago, is one of the sky's most famous "star wrecks." For decades, most astronomers have regarded it as the steadiest beacon at X-...

  5. Minimal incorporation of Deepwater Horizon oil by estuarine filter feeders.

    PubMed

    Fry, Brian; Anderson, Laurie C

    2014-03-15

    Natural abundance carbon isotope analyses are sensitive tracers for fates and use of oil in aquatic environments. Use of oil carbon in estuarine food webs should lead to isotope values approaching those of oil itself, -27‰ for stable carbon isotopes reflecting oil origins and -1000‰ for carbon-14 reflecting oil age. To test for transfer of oil from the 2010 Deepwater Horizon spill into estuarine food webs, filter-feeding barnacles (Balanus sp.) and marsh mussels (Geukensia demissa) were collected from Louisiana estuaries near the site of the oil spill. Carbon-14 analyses of these animals from open waters and oiled marshes showed that oil use was <1% and near detection limits estimated at 0.3% oil incorporation. Respiration studies showed no evidence for enhanced microbial activity in bay waters. Results are consistent with low dietary impacts of oil for filter feeders and little overall impact on respiration in the productive Louisiana estuarine systems.

  6. Design of Superconducting Parallel Bar Deflecting and Crabbing rf Structures

    SciTech Connect

    Jean Delayen, Haipeng Wang

    2009-05-01

    A new concept for a deflecting and crabbing rf structure based on half-wave resonant lines was introduced recently*. It offers significant advantages to existing designs and, because of it compactness, allows low frequency operation. This concept has been further refined and optimized for superconducting implementation. Results of this optimization and application to a 400 MHz crabbing cavity and a 499 MHz deflecting cavity are presented.

  7. Lincoln Co. Scrap Metal, Crab Orchard, Kentucky

    EPA Pesticide Factsheets

    The City of Crab Orchard, KY (population less than 1,000) received a $200,000 EPA Brownfields cleanup grant in 2010 to cleanup up the Lincoln County ScrapMetal property. The site, a former scrap metal recycler and general junkyard, was located in the middle of downtown. The city has experienced a dramatic decline in growth over the past few years. The abandoned two-acre site is located in the city’s center, directly across the street from City Hall. It is the largest property on Main Street. The property was an eyesore, and posed potential health risks to area residents, and deterred investment. Its blighted status did little to help the commercial and private properties that surround it. The site was also home to a dilapidated building that once served as the Odd Fellows meeting hall.

  8. Crab pulsar timing 1982-87

    NASA Astrophysics Data System (ADS)

    Lyne, A. G.; Pritchard, R. S.; Smith, F. G.

    1988-08-01

    Observations of the arrival times of pulses from the pulsar in the Crab Nebula over a six-year interval are presented. The data are intended to permit the investigation of the interior of the neutron star through the study of glitches and timing noise and to provide an ephemeris for high-energy observations. The first and second frequency derivatives provide a value for the braking index of n = 2.509 + or - 0.001, which is consistent with previous observations. The third frequency derivative can now be determined over an 18-yr span and is as expected for this braking index. The predominant deviations from a simple slow-down model form a sinusoid with a period of 20 months, attributable to an oscillation of the bulk of the neutron superfluid in the pulsar. One conspicuous glitch occurred in August, 1986 and the subsequent recovery was studied from only one hour after the event.

  9. The Crab-like supernova remnants

    NASA Technical Reports Server (NTRS)

    Seward, Frederick D.

    1989-01-01

    Recent observational and theoretical investigations of Galactic and extragalactic SNRs suspected of having neutron central stars are reviewed, with an emphasis on Einstein X-ray observations. Sections are devoted to the Crab Nebula and its twin SNR 0540-69.3, SNR with observationally well determined and indistinct central X-ray nebulae, SNR with weak and strong unresolved internal X-ray sources, binary systems, and the relationship between X-ray and radio luminosity and pulsar energy loss. Consideration is given to radio pulsars, SNR with filled-center X-ray emission attributed to thermal processes, radio plerions and composite SNRs, MSH 15-56, and SNRs in the LMC. Extensive contour maps, sample optical images, and tables of numerical data are included.

  10. Visual motion processing subserving behavior in crabs.

    PubMed

    Tomsic, Daniel

    2016-12-01

    Motion vision originated during the Cambrian explosion more than 500 million years ago, likely triggered by the race for earliest detection between preys and predators. To successfully evade a predator's attack a prey must react quickly and reliably, which imposes a common constrain to the implementation of escape responses among different species. Thus, neural circuits subserving fast escape responses are usually straightforward and contain giant neurons. This review summarizes knowledge about a small group of motion-sensitive giant neurons thought to be central in guiding the escape performance of crabs to visual stimuli. The flexibility of the escape behavior contrasts with the stiffness of the optomotor response, indicating a task-dependent early segregation of visual pathways.

  11. OSSE observations of the Crab pulsar

    NASA Technical Reports Server (NTRS)

    Ulmer, M. P.; Matz, S. M.; Cameron, R. A.; Grabelsky, D. A.; Grove, J. E.; Johnson, W. N.; Jung, G. V.; Kinzer, R. L.; Kurfess, J. D.; Leising, M. D.

    1992-01-01

    Preliminary results are presented of the Compton Gamma Ray Observatory Oriented Scintillation Spectrometer Experiment (OSSE) observations of the Crab pulsar. The pulsar energy spectra and light curves are in general agreement with previous observations, validating the OSSE pulsar data acquisition modes and data analysis algorithms. The data suggest that the spectrum of the pulsar varies throughout the light curve. The 'interpulse' region has a slightly flatter spectrum in the approx. 60 to 250 keV region and a slightly steeper spectrum at higher energies than the two main pulses. No evidence was found for any lines in the spectra with a typical sensitivity of about 10(exp -4) photons/sq cm/s.

  12. Final Report for "Compact Crab Cavity Design"

    SciTech Connect

    Smithe, David N

    2012-11-08

    The goal of this project is to provide an innovative, new crab cavity design relevant to the MEIC. Through this work, we will provide comprehensive modeling of this new cavity design, including electromagnetic, thermal, and microphonic effects. One most likely candidate configuration is the design put forward by JLab and Lancaster University, UK, researchers known as the four-rod configuration. In the Phase I, Tech-X Corporation researchers performed analysis and design optimization and iteration, utilizing their state-of-the art time-domain particle-in-cell software, on a 400 MHz design for the LHC by JLab and Lancaster University, UK, researchers known as the four-rod design.

  13. [Application of electron spin resonance spectroscopy for the detection of irradiated crustaceans (prawn, shrimp, and crabs)].

    PubMed

    Kameya, Hiromi; Takatsuki, Satoshi; Matsuda, Rieko; Tsutsumi, Tomoaki; Todoriki, Setsuko

    2014-01-01

    Prawn, shrimp and crabs sold in Japan are mostly imported from overseas. Detection of irradiated crustaceans is very important for quality assurance. In this study, we used ESR to detect radiation-induced radicals after irradiation of prawn, shrimp and crabs of major species. No radiation-induced radicals were detected in prawn (black tiger prawn) or shrimp (white leg shrimp). Radiation-induced radicals due to hydroxyapatite were detected in the claws of snow crab, red king crab, and swimming crab. Our results indicate that ESR measurement on the claw parts of these three species of crab can be used to determine their irradiation history.

  14. Dusty globules in the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Grenman, T.; Gahm, G. F.; Elfgren, E.

    2017-03-01

    Context. Dust grains are widespread in the Crab Nebula. A number of small, dusty globules, are visible as dark spots against the background of continuous synchrotron emission in optical images. Aims: Our aim is to catalogue such dusty globules and investigate their properties. Methods: From existing broad-band images obtained with the Hubble Space Telescope, we located 92 globules, for which we derived positions, dimensions, orientations, extinctions, masses, proper motions, and their distributions. Results: The globules have mean radii ranging from 400 to 2000 AU and are not resolved in current infrared images of the nebula. The extinction law for dust grains in these globules matches a normal interstellar extinction law. Derived masses of dust range from 1 to 60 × 10-6M⊙, and the total mass contained in globules constitute a fraction of approximately 2% or less of the total dust content of the nebula. The globules are spread over the outer part of the nebula, and a fraction of them coincide in position with emission filaments, where we find elongated globules that are aligned with these filaments. Only 10% of the globules are coincident in position with the numerous H2-emitting knots found in previous studies. All globules move outwards from the centre with transversal velocities of 60 to 1600 km s-1, along with the general expansion of the remnant. We discuss various hypotheses for the formation of globules in the Crab Nebula. Based on observations collected with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute.

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

    EPA Pesticide Factsheets

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

  16. Effects of chlorobrominated and chlorinated cooling waters on estuarine organisms

    SciTech Connect

    Liden, L.H.; Burton, D.T.; Bongers, L.H.; Holland, A.F.

    1980-01-01

    Research report:Continuous-flow bioassays were conducted during August 1976 to compare the effects of chlorobrominated and chlorinated condenser cooling effluents on several selected estuarine food-chain organisms. Two fish species, two bivalve species, a copepod, and naturally occurring phytoplankton communities were studied. Toxic effects of chlorobrominated and chlorinated power plant cooling waters on estuarine organisms appear to be similar with respect to the lethal and sublethal response indicators used in the study. However, more comparative tests must be conducted to define any differences in toxicities of bromine chloride or chlorine residual oxidants. (50 references, 5 tables)

  17. Remote sensing of estuarine fronts and their effects on pollutants

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator); Polis, D. F.

    1975-01-01

    The author has identified the following significant results. Imagery from LANDSAT 1 and 2 proved valuable in determining the location, type, and extent of estuarine fronts under different tidal conditions. Neither ships nor aircraft alone could provide as complete, synoptic, and repetitive an overview as did the satellites. Since estuarine fronts influence the movement of oil slicks and dispersion of other pollutants, cleanup operations depending on real time use of oil slick movement prediction models will benefit not only from aircraft tracking the actual slicks but also from real time satellite observations of surface currents and the location of frontal systems.

  18. Commercially Important Meroplankton of the Lower Chesapeake Bay and Proposed Norfolk Disposal Site. I. Blue Crabs, Rock Crabs and Oysters.

    DTIC Science & Technology

    1985-01-01

    and 7 (k) ............ .. 25 5 Abundance (#/m3 ) of Crassostrea virginica from oblique tows (153 u mesh) at the Bay mouth Stations: east of the...f - -f -) - - - - -n -i -) .- -.- Information accumulated over the past seven decades indicates that larvae of Crassostrea virginica migrate in...O7Wcommercial importance such as oysters ( Crassostrea vir_.inica), blue crab (Callinectes sapidus), and possibly, the rock crab (Cancer irroratus). A

  19. Biochemical and physiological responses after exposure to microcystins in the crab Chasmagnathus granulatus (Decapoda, Brachyura).

    PubMed

    Dewes, L J; Sandrini, J Z; Monserrat, J M; Yunes, J S

    2006-10-01

    Microcystins are usually the predominant cyanotoxins present in both drinking and recreational waters after cyanobacterial blooms. Their classic toxic effect is hepatotoxicity through inhibition of serine/threonine phosphatases. However, recent studies also reported oxidative stress generation and disruption of ion regulation in aquatic organisms after microcystins exposure. In the present study, aqueous extracts of Microcystis aeruginosa were administered to the estuarine crab Chasmagnathus granulatus (Decapoda, Brachyura) by gavage in variable doses (from 34 to 860 microg kg(-1)) and exposure times (6, 12, and 72 h). A control group was exposed to saline solution. Analyzed variables included oxygen consumption, lipid peroxidation (LPO), enzyme activities (glutathione S-transferases or GST; alanine aminotransferase or ALT; aspartate aminotransferase or AST; and lactate dehydrogenase or LDH), glycogen, and microcystins content. Oxygen consumption increased in organisms exposed for 12h to 860 microg kg(-1) of microcystins and a similar result was observed after 72 h at doses equal to or higher than 34 microg kg(-1). LPO levels increased in doses equal to or higher than 34 microg kg(-1) after 72 h. GST and LDH activities increased after 12 h (at a dose of 860 microg kg(-1)), but ALT and AST activities remained unaltered in all experimental conditions. Glycogen content decreased after 72 h exposure at doses equal to or higher than 172 microg kg(-1). After 12h of exposure to 860 microg kg(-1) of microcystins, the concentration found in the hepatopancreas of C. granulatus was 13.17+/-0.56 microg kg(-1). In crabs exposed to doses higher than 172 microg kg(-1) during 72 h this value raised to 32.14+/-4.12 microg kg(-1). The obtained results indicated that microcystins exposure led the tissue to an oxidative stress condition (high LPO levels), at least in part favored by the augment of oxygen consumption, altering the glycogen metabolism. GST responses were only observed

  20. Molecular Approach to Microbiological Examination of Water Quality in the Grand Bay National Estuarine Research Reserve (NERR) in Mississippi, USA.

    PubMed

    Kishinhi, Stephen S; Tchounwou, Paul B; Farah, Ibrahim O

    2013-01-01

    Grand Bay National Estuarine Research Reserve (NERR) is an important ecosystem in the Mississippi Gulf Coast. It serves as important nursery areas for juveniles of many species of fish. The bay is also used for fishing, crabbing, oyster togging, boating as well as recreation. Like in other aquatic environments, this bay may be contaminated by microorganisms including pathogenic bacteria. The objective of this study was to evaluate the microbiological quality of water in the Grand Bay NERR and determine the levels and potential source(s) of human fecal pollution. To achieve this goal, water samples were collected aseptically every month in Bayou Heron, Bayou Cumbest, Point Aux Chenes Bay and Bangs Lake. Enterococci were concentrated from water samples by membrane filtration according to the methodology outlined in USEPA Method 1600. After incubation, DNA was extracted from bacteria colonies on the membrane filters by using QIAamp DNA extraction kit. Water samples were also tested for the presence of traditional indicator bacteria including: heterotrophic plate count, total coliforms, fecal coliforms, and Enterococcus bacteria. The marker esp gene was detected in one site of Bayou Cumbest, an area where human populations reside. Data from this study indicates higher concentrations of indicator bacteria compared to the recommended acceptable levels. Presence of esp marker and high numbers of indicator bacteria suggest a public health concern for shellfish and water contact activities. Hence, control strategies should be developed and implemented to prevent further contamination of the Grand bay NERR waters.

  1. Fiddler crabs (Uca spp.) as model hosts for laboratory infections of Hematodinium perezi.

    PubMed

    O'Leary, Patricia A; Shields, Jeffrey D

    2017-02-01

    The parasitic dinoflagellate, Hematodinium perezi, negatively impacts the commercially important blue crab, Callinectes sapidus. The parasite is a host generalist, but it has not been reported from littoral fiddler crabs living within a few meters of habitat known to harbor infected blue crabs. In the first study, populations of three species of fiddler crab were screened for natural infections. The infection status of field-collected and lab-inoculated crabs was determined by screening fresh hemolymph with a 0.3% neutral red solution. Fiddler crabs were collected by hand in an area adjacent to where infected blue crabs were commonly collected. None of the 431 fiddlers had natural infections. In two separate studies, three species of fiddler crabs, Uca minax, U. pugnax, and U. pugilator, were evaluated for their susceptibility to H. perezi via inoculation of trophic stages. Uca minax inoculated with 10,000 cells of H. perezi were monitored for progression of the parasite. During hemolymph screenings of disease progression, filamentous trophonts, ameboid trophonts, and clump colonies were observed, indicative of active infections. In the second study, the minimum infective dose in U. minax was investigated. Fiddler crabs were inoculated with 0, 100, 1000, or 10,000 cells per crab. The minimum dose was determined to be approximately 1000 ameboid trophonts per crab. All three species of fiddler crab were susceptible to H. perezi via inoculation. The parasite was serially transferred from fiddler crabs to blue crabs without loss of infectivity. Survival studies indicated similar progression patterns to those observed in blue crabs. Based on our results fiddler crabs can serve as a laboratory model for investigating H. perezi infections and may be useful for comparative studies with blue crabs.

  2. Copper toxicity in the crab, Scylla serrata, copper levels in tissues and regulation after exposure to a copper-rich medium

    SciTech Connect

    Arumugam, M.; Ravindranath, M.H.

    1987-10-01

    In the decapod crustaceans copper is distributed in various tissues. In these animals the tissue copper generally exists in four forms; ionic, bound to proteins, lipids and membrane. In the estuarine crab Scylla serrata, the haemolymph copper exists only in association with proteins, whereas in the hepatopancreas it exists in all the four forms and in gills it exists in all the forms except in combination with lipids. Although food is the major source of copper in decapod crustaceans evidence indicate that copper may be directly obtained from the environment. It was postulated earlier that in Scylla serrata the haemolymph and hepatopancreas may be involved in copper regulation. In the present work the authors have studied the nature and levels of copper in different tissues after exposing the crabs to copper-rich medium. The results indicate the relative importance of various tissues in accumulation an the possible mechanisms of regulation of the environmental copper. Besides, as a pre-requisite for studies of this kind, the toxic levels for different forms of copper were estimated since the form of toxicant is known to influence the toxicity to the decapod crustaceans.

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

    PubMed

    Amaral, Maria Rosimere Xavier; Albrecht, Marc; McKinley, Alan Shane; de Carvalho, Adriana Márcia Ferreira; de Sousa Junior, Severino Cavalcante; Diniz, Fabio Mendonça

    2015-08-19

    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.

  4. Recruitment variation of eastern Bering Sea crabs: Climate-forcing or top-down effects?

    NASA Astrophysics Data System (ADS)

    Zheng, Jie; Kruse, Gordon H.

    2006-02-01

    During the last three decades, population abundances of eastern Bering Sea (EBS) crab stocks fluctuated greatly, driven by highly variable recruitment. In recent years, abundances of these stocks have been very low compared to historical levels. This study aims to understand recruitment variation of six stocks of red king ( Paralithodes camtschaticus), blue king ( P. platypus), Tanner ( Chionoecetes bairdi), and snow ( C. opilio) crabs in the EBS. Most crab recruitment time series are not significantly correlated with each other. Spatial distributions of three broadly distributed crab stocks (EBS snow and Tanner crabs and Bristol Bay red king crab) have changed considerably over time, possibly related in part to the regime shift in climate and physical oceanography in 1976-1977. Three climate-forcing hypotheses on larval survival have been proposed to explain crab recruitment variation of Bristol Bay red king crab and EBS Tanner and snow crabs. Some empirical evidence supports speculation that groundfish predation may play an important role in crab recruitment success in the EBS. However, spatial dynamics in the geographic distributions of groundfish and crabs over time make it difficult to relate crab recruitment strength to groundfish biomass. Comprehensive field and spatially explicit modeling studies are needed to test the hypotheses and better understand the relative importance and compound effects of bottom-up and top-down controls on crab recruitment.

  5. Tungsten-molybdenum fractionation in estuarine environments

    NASA Astrophysics Data System (ADS)

    Mohajerin, T. Jade; Helz, George R.; Johannesson, Karen H.

    2016-03-01

    Dissolved tungsten (W) and molybdenum (Mo) concentrations were measured in surface waters and sediment pore waters of Terrebonne Bay, a shallow estuary in the Mississippi River delta, to investigate the biogeochemical processes that fractionate these Group 6 elements relative to one another during transit from weathering to sedimentary environments. Although many of the chemical properties of W and Mo are similar, the two elements behave autonomously, and the fractionation mechanisms are only partly understood. In sulfidic pore waters, dissolved Mo is depleted relative to river water-seawater mixtures, whereas dissolved W is >10-fold enriched. Reductive dissolution of poorly crystalline phases like ferrihydrite, which is a preferential host of W relative to Mo in grain coatings on river-borne particles, can explain the dissolved W enrichment. Dissolved W becomes increasingly enriched as H2S(aq) rises above about 60 μM due to transformation of WO42- to thiotungstates as well as to additional reductive dissolution of phases that host W. In contrast, as rising sulfide transforms MoO42- to thiomolybdates in pore waters, dissolved Mo is suppressed, probably owing to equilibration with an Fe-Mo-S phase. This putative phase appears to control the aqueous ion product, Q = [Fe2+][MoS42-]0.6 [H2S0]0.4/[H+]0.8, at a value of 10-7.78. Concentrations of dissolved W and Mo in pore waters bear no relation to concentrations in surface waters of the same salinity. In surface waters, dissolved Mo is nearly conserved in the estuarine mixing zone. Dissolved W appears also to be conserved except for several cases where W may have been enhanced by exchange with underlying, W-rich pore waters. With increasing salinity, the molar Mo/W ratio rises from about 10 to about 1000 in surface waters whereas it is mostly <10 in underlying pore waters and in highly sulfidic pore waters is mostly near 1. Differences in two chemical properties may account for this fractionation of Mo with respect to

  6. The densities of Changjiang estuarine waters

    NASA Astrophysics Data System (ADS)

    Chen, Guohua; Hu, Bolu; Zhang, Lijun; Ji, Rong; Jin, Jiancheng; Chen, Bing

    1993-09-01

    In order to check the validity of the International Equation of State of Seawater set up by the UNESCO in 1980 for application to China coastal waters, the authors measured the relative density of Changjiang estuarine seawater and seawater solutions diluted with the Changjiang River water at one atmosphere from 5 35 salinity under 15 24°C with a high precision magnetic float densimeter designed by them. The average standard deviation of measured values was ±2.3×10-3 kgm-3. the statistical results showed that for all samples from the Changjiang estuary, the measured density with the densimeter was always higher than the density calculated by the UNESCO equation. The average differences, for dry season and flood season seawater samples were (+6.3±2.3)×10-3kgm-3 and (+8.1±2.3)×10-3kgm-3, respectively. The average difference between the measured and calculated (from the UNESCO equation) density increased linearly as salinity decreased and became +47.2×10-3 kgm-3 at the Changjiang River water salinity limit of around 0.134. A linear correlation was found between this average difference and the [Ca2+]/s ratio value. The experimental average values of [Ca2+]/s, [SO{4/2-}]/s, [Mg2+]/s, and [Sr2+]/s were 0.01183±1.0×10-4, 0.07698±1.7×10-4, 0.03743±8.1×10-5 and 2.26×10-4, respectively, at sample salinities of 30 to 35. The experimental value of [Ca2+]/s for the Wuhu Changjiang River water was 0.2597. The resulting densities of all samples were then fitted to an equation of the form d- d w = B 1s1/2+ B 2s+ B 3s3/2+ B 4s2 where d w is the density of SMOW and B 1, B 2, B 3 and B 4 are temperature-dependent parameters. The average standard deviation between calculated densities of this equation and experimental values was ±3.9×10-3 kgm-3.

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

    EPA Science Inventory

    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 ...

  8. Shell use: an adaptation for emigration from the sea by the coconut crab.

    PubMed

    Reese, E S

    1968-07-26

    The coconut crab. Birgus latro (L.) emigrates from the sea during the postlarval glaucothoe stage. Glaucothoes show ancestral hermit crab behavior of living in empty gastropod shells which protect them during this vulnerable time.

  9. INDEX OF ESTUARINE BENTHIC INTEGRITY FOR GULF OF MEXICO ESTUARIES

    EPA Science Inventory

    A benthic index for northern Gulf of Mexico estuaries has been developed and successfully validated by the Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) in the Louisianian Province. The benthic index is a useful indicator of estuarine condition that provi...

  10. Survey of three-dimensional numerical estuarine models

    USGS Publications Warehouse

    Cheng, Ralph T.; Smith, Peter E.

    1989-01-01

    This paper surveys the existing 3-D estuarine hydrodynamic and solute transport models by a review of the commonly used assumptions and approximations, and by an examination of the methods of solution. The model formulations, methods of solution, and known applications are surveyed and summarized in tables. In conclusion, the authors present their modeling philosophy and suggest future research needs.

  11. 75 FR 60720 - National Estuarine Research Reserve System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Estuarine Research Reserve System Correction In notice document 2010-24341 appearing on page 59696 in the issue of Tuesday, September 28, 2010 make...

  12. Field Study Manual to Freshwater and Estuarine Habitats.

    ERIC Educational Resources Information Center

    Georgia State Dept. of Education, Atlanta.

    This field studies manual, developed by biology students in the 1971 Georgia Governor's Honors Program, was designed for collection of data pertinent to freshwater and estuarine habitats. In addition to the various methods of sampling the ecosystem and for quantification of the data, instructions for dividing the field study into three logical…

  13. Marine and Estuarine Ecology. Man and the Gulf of Mexico.

    ERIC Educational Resources Information Center

    Irby, Bobby N.; And Others

    "Man and the Gulf of Mexico (MGM)" is a marine science curriculum developed to meet the marine science needs of tenth through twelfth grade students in Mississippi and Alabama schools. This MGM unit, which focuses on marine and estuarine ecology, is divided into six sections. The first section contains unit objectives, discussions of the…

  14. Salt Marsh--Estuarine Ecosystem: A Liquid Asset

    ERIC Educational Resources Information Center

    Steever, E. Zell

    1977-01-01

    A comprehensive description of the salt marsh-estuarine ecosystem is provided. Topics discussed include: the general geologic history and formation of this ecosystem; physical and chemical parameters; variety; primary productivity; tidal zones; kind, sizes and abundance of vegetation; and the environmental factors influencing vegetation. (BT)

  15. Ordination of the estuarine environment: What the organism experiences

    EPA Science Inventory

    Investigators customarily schedule estuary sampling trips with regard to a variety of criteria, especially tide stage and the day-night cycle. However, estuarine organisms experience a wide suite of continuously changing tide and light conditions. Such organisms may undertake i...

  16. Location of volatile odor sources by ghost crabOcypode quadrata (Fabricius).

    PubMed

    Wellins, C A; Rittschof, D; Wachowiak, M

    1989-04-01

    The ghost crab,Ocypode quadrata, was tested in the field for its ability to locate sources of volatile cues. The pure compound skatole, 3-methylindole, was a potent attractant. Crabs also located sources of complex odors such as dead fish,Lutjanus campechanus, dead mole crabs,Emerita talpoida; and peeled bananas. Ghost crabs possess concealed and reduced antennules that may not be the primary olfactory organs. Chemosensory hairs borne on the dactyls may be the primary detection system.

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

    SciTech Connect

    Verdu-Andres, S.; Skaritka, J.; Wu, Q.; Xiao, B.; Belomestnykh, S.; Ben-Zvi, I.; Alberty, L.; Artoos, K.; Calaga, R.; Capatina, O.; Capelli, T.; Carra, F.; Leuxe, R.; Kuder, N.; Zanoni, C.; Li, Z.; Ratti, A.

    2015-05-03

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

  18. Juvenile fish condition in estuarine nurseries along the Portuguese coast

    NASA Astrophysics Data System (ADS)

    Vasconcelos, R. P.; Reis-Santos, P.; Fonseca, V.; Ruano, M.; Tanner, S.; Costa, M. J.; Cabral, H. N.

    2009-03-01

    Connectivity between estuarine fish nurseries and coastal adult habitats can be affected by variations in juvenile growth and survival. Condition indices are renowned proxies of juvenile nutritional status and growth rates and are valuable tools to assess habitat quality. Biochemical (RNA:DNA ratio) and morphometric (Fulton's condition factor K) condition indices were determined in juveniles of Solea solea, Solea senegalensis, Platichthys flesus, Diplodus vulgaris and Dicentrarchus labrax collected in putative nursery areas of nine estuaries along the Portuguese coast (Minho, Douro, Ria de Aveiro, Mondego, Tejo, Sado, Mira, Ria Formosa and Guadiana) in the Spring and Summer of two consecutive years (2005 and 2006) with distinct climatic characteristics. Individual condition showed significant variation amongst species. The combined use of both condition indices highlighted the low correlation between them and that RNA:DNA had a higher sensitivity. RNA:DNA varied between years but overall the site relative patterns in condition were maintained from one year to the other. Higher RNA:DNA values were found in Spring than in Summer in most species. Intra-estuarine variation also occurred in several cases. Species specific trends in the variability of condition amongst estuaries were highlighted. Some estuaries had higher juvenile condition for more than one species but results did not reveal an identical trend for all species and sites, hindering the hypotheses of one estuarine nursery promoting superior growth for all present species. Significant correlations were found between condition indices, juvenile densities and environmental variables (water temperature, salinity and depth) in the estuarine nurseries. These influenced juvenile nutritional condition and growth, contributing to the variability in estuarine nursery habitat quality. Management and conservation wise, interest in multi-species approaches is reinforced as assessments based on a single species may not

  19. Characterization of the Crab Pulsar's Timing Noise

    NASA Technical Reports Server (NTRS)

    Scott, D. M.; Finger, M. H.; Wilson, C. A.

    2003-01-01

    We present a power spectral analysis of the Crab pulsar's timing noise, mainly using radio measurements from Jodrell Bank taken over the period 1982-1989, an interval bounded by sparse data sampling and a large glitch. The power spectral analysis is complicated by nonuniform data sampling and the presence of a steep red power spectrum that can distort power spectra measurement by causing severe power 'leakage'. We develop a simple windowing method for computing red noise power spectra of uniformly sampled data sets and test it on Monte Carlo generated sample realizations of red power-law noise. We generalize time-domain methods of generating power-law red noise with even integer spectral indices to the case of noninteger spectral indices. The Jodrell Bank pulse phase residuals are dense and smooth enough that an interpolation onto a uniform time series is possible. A windowed power spectrum is computed revealing a periodic or nearly periodic component with a period of 568 +/- 10 days and a l/f(exp 3) power-law noise component in pulse phase with a noise strength S(sub infinity)=(1.24 +/- 0.067) x 10(exp 16) cycles(exp 2)/sec(exp 2) over the analysis frequency range f=0.003- 0.1 cycles/day. This result deviates from past analyses which characterized the pulse phase timing residuals as either l/f(sub 4) power-law noise or a quasiperiodic process. The analysis was checked using the Deeter polynomial method of power spectrum estimation that was developed for the case of nonuniform sampling, but has lower spectral resolution. The timing noise is consistent with a torque noise spectrum rising with analysis frequency as f implying blue torque noise, a result not predicted by current models of pulsar timing noise. If the periodic or nearly periodic component is due to a binary companion, we find a mass function f(M) = (6.8 +/- 2.4) x 10(exp -16) solar mass and a companion mass, M(sub c) is greater than or equal to 3.2 solar mass assuming a Crab pulsar mass of 1.4 solar

  20. 50 CFR 648.263 - Red crab possession and landing restrictions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Management Measures for the Atlantic Deep-Sea Red Crab Fishery § 648.263 Red crab possession and landing...-processing prohibition. No person may fully process at sea, possess, or land, fully-processed red crab. (5... Management Unit. (2) Full-processing prohibition. No person may fully process at sea, possess, or land,...

  1. 50 CFR 648.263 - Red crab possession and landing restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Management Measures for the Atlantic Deep-Sea Red Crab Fishery § 648.263 Red crab possession and landing...-processing prohibition. No person may fully process at sea, possess, or land, fully-processed red crab. (5... Management Unit. (2) Full-processing prohibition. No person may fully process at sea, possess, or land,...

  2. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  3. 50 CFR Table 3a to Part 680 - Crab Delivery Condition Codes

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Crab Delivery Condition Codes 3a Table 3a... ZONE OFF ALASKA Pt. 680, Table 3a Table 3a to Part 680—Crab Delivery Condition Codes Code Description 01 Whole crab, live. 79 Deadloss....

  4. 50 CFR Table 3a to Part 680 - Crab Delivery Condition Codes

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Crab Delivery Condition Codes 3a Table 3a... ZONE OFF ALASKA Pt. 680, Table 3a Table 3a to Part 680—Crab Delivery Condition Codes Code Description 01 Whole crab, live. 79 Deadloss....

  5. 50 CFR 648.262 - Accountability measures for red crab limited access vessels.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Accountability measures for red crab... UNITED STATES Management Measures for the Atlantic Deep-Sea Red Crab Fishery § 648.262 Accountability measures for red crab limited access vessels. (a) Closure authority. NMFS shall close the EEZ to...

  6. 50 CFR 648.262 - Accountability measures for red crab limited access vessels.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Accountability measures for red crab... UNITED STATES Management Measures for the Atlantic Deep-Sea Red Crab Fishery § 648.262 Accountability measures for red crab limited access vessels. (a) Closure authority. NMFS shall close the EEZ to...

  7. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  8. 50 CFR Table 3a to Part 680 - Crab Delivery Condition Codes

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Crab Delivery Condition Codes 3a Table 3a... ZONE OFF ALASKA Pt. 680, Table 3a Table 3a to Part 680—Crab Delivery Condition Codes Code Description 01 Whole crab, live. 79 Deadloss....

  9. 50 CFR 648.262 - Accountability measures for red crab limited access vessels.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Accountability measures for red crab... UNITED STATES Management Measures for the Atlantic Deep-Sea Red Crab Fishery § 648.262 Accountability measures for red crab limited access vessels. (a) Closure authority. NMFS shall close the EEZ to...

  10. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  11. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  12. 40 CFR 408.50 - Applicability; description of the remote Alaskan crab meat processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... remote Alaskan crab meat processing subcategory. 408.50 Section 408.50 Protection of Environment... PROCESSING POINT SOURCE CATEGORY Remote Alaskan Crab Meat Processing Subcategory § 408.50 Applicability; description of the remote Alaskan crab meat processing subcategory. The provisions of this subpart...

  13. 76 FR 25545 - Safety Zone; Blue Crab Festival Fireworks Display, Little River, Little River, SC

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-05

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Blue Crab Festival Fireworks Display... Carolina during the Blue Crab Festival Fireworks Display on Friday, ] May 13, 2011. The safety zone is... this rule because the Coast Guard did not receive notice of the Blue Crab Festival Fireworks...

  14. 40 CFR 408.20 - Applicability; description of the conventional blue crab processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... conventional blue crab processing subcategory. 408.20 Section 408.20 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Conventional Blue Crab Processing Subcategory § 408.20 Applicability; description of the conventional blue crab processing subcategory. The provisions of this subpart are applicable to...

  15. 40 CFR 408.20 - Applicability; description of the conventional blue crab processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... conventional blue crab processing subcategory. 408.20 Section 408.20 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Conventional Blue Crab Processing Subcategory § 408.20 Applicability; description of the conventional blue crab processing subcategory. The provisions of this subpart are applicable to...

  16. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Sound blue king crab. NVDC means the U.S. Coast Guard's National Vessel Documentation Center located in...) Crab species program. 600.1103 Section 600.1103 Wildlife and Fisheries FISHERY CONSERVATION AND... Aleutian Islands (BSAI) Crab species program. (a) Purpose. This section's purpose is to implement...

  17. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

  18. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

  19. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

  20. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Sound blue king crab. NVDC means the U.S. Coast Guard's National Vessel Documentation Center located in...) Crab species program. 600.1103 Section 600.1103 Wildlife and Fisheries FISHERY CONSERVATION AND... Aleutian Islands (BSAI) Crab species program. (a) Purpose. This section's purpose is to implement...

  1. 40 CFR 408.20 - Applicability; description of the conventional blue crab processing subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... conventional blue crab processing subcategory. 408.20 Section 408.20 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Conventional Blue Crab Processing Subcategory § 408.20 Applicability; description of the conventional blue crab processing subcategory. The provisions of this subpart are applicable to...

  2. 40 CFR 408.20 - Applicability; description of the conventional blue crab processing subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... conventional blue crab processing subcategory. 408.20 Section 408.20 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Conventional Blue Crab Processing Subcategory § 408.20 Applicability; description of the conventional blue crab processing subcategory. The provisions of this subpart are applicable to...

  3. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

  4. 40 CFR 408.20 - Applicability; description of the conventional blue crab processing subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... conventional blue crab processing subcategory. 408.20 Section 408.20 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Conventional Blue Crab Processing Subcategory § 408.20 Applicability; description of the conventional blue crab processing subcategory. The provisions of this subpart are applicable to...

  5. 40 CFR 408.30 - Applicability; description of the mechanized blue crab processing subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... mechanized blue crab processing subcategory. 408.30 Section 408.30 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Mechanized Blue Crab Processing Subcategory § 408.30 Applicability; description of the mechanized blue crab processing subcategory. The provisions of this subpart are applicable to...

  6. Patterns of activity expressed by juvenile horseshoe crabs.

    PubMed

    Dubofsky, E A; Simpson, S D; Chabot, Christopher C; Watson, Winsor H

    2013-09-01

    Adult American horseshoe crabs, Limulus polyphemus, possess endogenous circadian and circatidal clocks controlling visual sensitivity and locomotion, respectively. The goal of this study was to determine the types of activity rhythms expressed by juvenile horseshoe crabs (n = 24) when exposed to a 14:10 light/dark cycle (LD) for 10 days, followed by 10 days of constant darkness (DD). Horseshoe crab activity was recorded with a digital time-lapse video system that used an infrared-sensitive camera so animals could be monitored at night. In LD, 15 animals expressed daily patterns of activity, 6 displayed a circatidal pattern, and the remaining 3 were arrhythmic. Of the 15 animals with daily patterns of locomotion, 7 had a significant preference (P < 0.05) for diurnal activity and 3 for nocturnal activity; the remainder did not express a significant preference for day or night activity. In DD, 13 horseshoe crabs expressed circatidal rhythms and 8 maintained a pattern of about 24 h. Although these results suggest the presence of a circadian clock influencing circatidal patterns of locomotion, these apparent circadian rhythms may actually represent the expression of just one of the two bouts of activity driven by the putative circalunidian clocks that control their tidal rhythms. Overall, these results indicate that, like adults, juvenile horseshoe crabs express both daily and tidal patterns of activity and that at least one, and maybe both, of these patterns is driven by endogenous clocks.

  7. ELEMENT DISTRIBUTIONS IN THE CRAB NEBULA

    SciTech Connect

    Satterfield, Timothy J.; Katz, Andrea M.; Sibley, Adam R.; MacAlpine, Gordon M.; Uomoto, Alan

    2012-07-15

    Images of the Crab Nebula have been obtained through custom interference filters that transmit emission from the expanding supernova remnant in He II {lambda}4686, H{beta}, He I {lambda}5876, [O I] {lambda}{lambda}6300, 6364, [N II] {lambda}{lambda}6548, 6583, [S II] {lambda}{lambda}6716, 6731, [S III] {lambda}9069, and [C I] {lambda}{lambda}9823, 9850. We present both raw and flux-calibrated emission-line images. Arrays of 19,440 photoionization models, with extensive input abundance ranges, were matched pixel by pixel to the calibrated data in order to derive corresponding element abundance or mass-fraction distributions for helium, carbon, nitrogen, oxygen, and sulfur. These maps show distinctive structure, and they illustrate regions of gas in which various stages of nucleosynthesis have apparently occurred, including the CNO cycle, helium burning, carbon burning, and oxygen burning. It is hoped that the calibrated observations and chemical abundance distribution maps will be useful for developing a better understanding of the precursor star evolution and the supernova explosive process.

  8. Unpulsed Optical Emission from the Crab Pulsar

    NASA Astrophysics Data System (ADS)

    Golden, A.; Shearer, A.; Beskin, G. M.

    2000-05-01

    Based on observations of the Crab pulsar using the TRIFFID high-speed imaging photometer in the UBV bands using the Special Astrophysical Observatory's 6 m telescope in the Russian Caucasus, we report the detection of pronounced emission during the so-called off phase of emission. Following de-extinction, this unpulsed component of emission is shown to be consistent with a power law with an exponent of α=-0.60+/-0.37, the uncertainty being dominated by the error associated with the independent CCD photometry used to reference the TRIFFID data. This suggests a steeper power-law form than that reported elsewhere in the literature for the total integrated spectrum, which is essentially flat with α~0.1, although the difference in this case is only significant at the <=2 σ level. Deeper reference integrated and TRIFFID phase-resolved photometry, in these bands in conjunction with further observations in the UV and R region, would constrain this fit further. Based on observations using the 6 m telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences in Nizhnii Arkhyz, Russia.

  9. Dishonest signalling in a fiddler crab.

    PubMed

    Backwell, P R; Christy, J H; Telford, S R; Jennions, M D; Passmore, N I

    2000-04-07

    Animal communication theory predicts that low-frequency cheating should be common in generally honest signalling systems. However, perhaps because cheats are designed to go undetected, there are few examples of dishonest signals in natural populations. Here we present what we believe is the first example of a dishonest signal which is used commonly by males to attract mates and fight sexual rivals. After losing their large claw male fiddler crabs (Uca annulipes) grow a new one which has less mass, is a less effective weapon and costs less to use in signalling than an equivalent-length claw of the original form. Males with original claws do not differentially fight males with regenerated claws even though they are likely to win. Regenerated claws effectively bluff fighting ability and deter potential opponents before they fight. During mate searching, females do not discriminate against males with low-mass, regenerated claws, indicating that they are deceived as to the true costs males pay to produce sexual signals. Up to 44% of males in natural populations have regenerated claws, a level unanticipated by current signalling theory. The apparent rarity of cheating may be an artefact of the usual difficulty of detecting cheats and dishonesty may be quite common.

  10. Evaluation of a small beach nourishment project to enhance habitat suitability for horseshoe crabs

    NASA Astrophysics Data System (ADS)

    Jackson, Nancy L.; Smith, David R.; Tiyarattanachai, Ronnachai; Nordstrom, Karl F.

    2007-09-01

    This field study evaluates the effect of nourishing an estuarine beach with gravel to enhance spawning rates by horseshoe crabs. A total of 564 m 3 of coarse sand and gravel were emplaced in two 90 m-long treatment segments at Bowers Beach, Delaware, USA from 9 to 11 April 2002. Field data were gathered between 6 April and 24 May 2002 to characterize the two fill segments and the un-nourished segments between them as well as two control segments at the adjacent Ted Harvey Beach. Sediment samples were taken from the foreshore surface and at depth before and after the nourishment. Bay water levels, wave heights, and beach ground water characteristics were monitored over a 12-hour tidal cycle at one of the nourished (15 May 2002) and the unnourished segment (16 May 2002) at Bowers Beach and at one of the control segments at Ted Harvey Beach (21 May 2002) using piezometers and pressure transducers inserted in wells. The beaches were cored to estimate the density of horseshoe crab eggs deposited during the spawning season. Horseshoe crab eggs were buried in pouches at 0.15 to 0.20 m depth for 30 to 40 days to evaluate their survival in developing into embryo or larval stage. Bulk sediment samples were taken to evaluate moisture characteristics near locations where egg pouches were buried. Density of spawning females at Bowers Beach was 1.04 m - 2 in 2001 and 1.20 m - 2 in 2002. These rates are lower than at Ted Harvey Beach but reveal an increase in spawning while Ted Harvey Beach underwent a considerable decrease (2.63 m - 2 to 1.35 m - 2 ). Sediments low on the foreshore remained nearly saturated throughout the tidal cycle at both beaches. The average hydraulic conductivity on the upper foreshore at the non-treatment section at Bowers Beach (0.19 cm s - 1 ) was less than at Ted Harvey Beach (0.27 cm s - 1 ), and the finer, better sorted sediments at depth at Bowers Beach resulted in a higher porosity, creating greater moisture retention potential. Egg development was

  11. Evaluation of a small beach nourishment project to enhance habitat suitability for horseshoe crabs

    USGS Publications Warehouse

    Jackson, N.L.; Smith, D.R.; Tiyarattanachai, R.; Nordstrom, K.F.

    2007-01-01

    This field study evaluates the effect of nourishing an estuarine beach with gravel to enhance spawning rates by horseshoe crabs. A total of 564??m3 of coarse sand and gravel were emplaced in two 90??m-long treatment segments at Bowers Beach, Delaware, USA from 9 to 11 April 2002. Field data were gathered between 6 April and 24 May 2002 to characterize the two fill segments and the un-nourished segments between them as well as two control segments at the adjacent Ted Harvey Beach. Sediment samples were taken from the foreshore surface and at depth before and after the nourishment. Bay water levels, wave heights, and beach ground water characteristics were monitored over a 12-hour tidal cycle at one of the nourished (15 May 2002) and the unnourished segment (16 May 2002) at Bowers Beach and at one of the control segments at Ted Harvey Beach (21 May 2002) using piezometers and pressure transducers inserted in wells. The beaches were cored to estimate the density of horseshoe crab eggs deposited during the spawning season. Horseshoe crab eggs were buried in pouches at 0.15 to 0.20??m depth for 30 to 40??days to evaluate their survival in developing into embryo or larval stage. Bulk sediment samples were taken to evaluate moisture characteristics near locations where egg pouches were buried. Density of spawning females at Bowers Beach was 1.04??m- 2 in 2001 and 1.20??m- 2 in 2002. These rates are lower than at Ted Harvey Beach but reveal an increase in spawning while Ted Harvey Beach underwent a considerable decrease (2.63??m- 2 to 1.35??m- 2). Sediments low on the foreshore remained nearly saturated throughout the tidal cycle at both beaches. The average hydraulic conductivity on the upper foreshore at the non-treatment section at Bowers Beach (0.19??cm s- 1) was less than at Ted Harvey Beach (0.27??cm s- 1), and the finer, better sorted sediments at depth at Bowers Beach resulted in a higher porosity, creating greater moisture retention potential. Egg development was

  12. 75 FR 49420 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ... United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications In... (TAC) and corresponding fleet days-at-sea (DAS) allocation for the Atlantic deep- sea red crab fishery... the implementing regulations for the Atlantic Deep- Sea Red Crab Fishery Management Plan...

  13. 76 FR 43658 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-21

    ... Alaska; Bering Sea and Aleutian Islands Crab Rationalization Cost Recovery Program AGENCY: National... under the Bering Sea and Aleutian Islands Crab Rationalization Program. This action is intended to provide holders of crab allocations with the fee percentage for the 2011/2012 crab fishing year so...

  14. 50 CFR 600.1104 - Bering Sea and Aleutian Islands (BSAI) crab species fee payment and collection system.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Pribilof blue king (the corresponding crab rationalization fishery is Pribilof red king and blue king crab), and (6) St. Matthew blue king (the corresponding crab rationalization fishery is also St. Matthew blue...) crab species fee payment and collection system. 600.1104 Section 600.1104 Wildlife and...

  15. 76 FR 68358 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-04

    ... Program, the western Aleutian Islands red king crab and Pribilof Islands red and blue king crab fisheries have failed to open, and the Saint Matthew Island blue king crab fishery has only been open during the... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program AGENCY:...

  16. 50 CFR 600.1104 - Bering Sea and Aleutian Islands (BSAI) crab species fee payment and collection system.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Pribilof blue king (the corresponding crab rationalization fishery is Pribilof red king and blue king crab), and (6) St. Matthew blue king (the corresponding crab rationalization fishery is also St. Matthew blue...) crab species fee payment and collection system. 600.1104 Section 600.1104 Wildlife and...

  17. 50 CFR 600.1104 - Bering Sea and Aleutian Islands (BSAI) crab species fee payment and collection system.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Pribilof blue king (the corresponding crab rationalization fishery is Pribilof red king and blue king crab), and (6) St. Matthew blue king (the corresponding crab rationalization fishery is also St. Matthew blue...) crab species fee payment and collection system. 600.1104 Section 600.1104 Wildlife and...

  18. 50 CFR 600.1104 - Bering Sea and Aleutian Islands (BSAI) crab species fee payment and collection system.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Pribilof blue king (the corresponding crab rationalization fishery is Pribilof red king and blue king crab), and (6) St. Matthew blue king (the corresponding crab rationalization fishery is also St. Matthew blue...) crab species fee payment and collection system. 600.1104 Section 600.1104 Wildlife and...

  19. 50 CFR 600.1104 - Bering Sea and Aleutian Islands (BSAI) crab species fee payment and collection system.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Pribilof blue king (the corresponding crab rationalization fishery is Pribilof red king and blue king crab), and (6) St. Matthew blue king (the corresponding crab rationalization fishery is also St. Matthew blue...) crab species fee payment and collection system. 600.1104 Section 600.1104 Wildlife and...

  20. 76 FR 49423 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ... the CR Program, the western Aleutian Islands red king crab and Pribilof Islands red and blue king crab fisheries have failed to open, and the Saint Matthew Island blue king crab fishery has only been open during... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program AGENCY:...

  1. [Study on the toxicity of horseshoe crabs in mice].

    PubMed

    Liao, Y; Li, X

    2000-05-30

    In order to study the toxicity of horseshoe crabs(tachypleus tridentatus and carcinoscorpius rotundicauda) in the sea of China, the extracts of tissues from tachypleus tridentatus and carcinoscorpius rotundicauda were injected into the abdominal cavity of mice for testing their poisoning effects. The results showed that the toxicity of carcinoscorpius rotundicauda was much higher than that of tachypleus tridentatus. The length of time from the injection to the death was much shorter for Carcinoscorpius rotundicauda than that for tachypleus tridentatus. The signs before death for Carcinoscorpius rotundicauda poisoning were restless, jumping and spasm but that for Tachypleus tridentatus was lethargy. The toxicity of adult horseshoe crabs was much higher than that of young horseshoe crabs.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Chandra Observations of the Crab: A Progress Report

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.

    2012-01-01

    Recently there have been two important findings concerning the Crab both of which are highlighted in this workshop. One finding was the discovery, using the AGILE and Fermi satellites, of gamma-ray flares from the direction of the Crab Nebula. The other finding was the variability, up to 7%, with time scales of the order of a year of the integrated hard X-ray emission. We have been using the Chandra X-Ray observatory to monitor the Crab on a monthly cadence since just after the 2010 September gamma-ray flare. We were also fortunate to trigger series of preplanned target of opportunity observations during the 2011 April flare. Our monitoring observations are on-going and will extend, at a minimum until the fall of 2012. We present an update and overview of these observations.

  4. Double lethal coconut crab (Birgus latro L.) poisoning.

    PubMed

    Maillaud, C; Lefebvre, S; Sebat, C; Barguil, Y; Cabalion, P; Cheze, M; Hnawia, E; Nour, M; Durand, F

    2010-01-01

    We report a double lethal coconut crab Birgus latro L. poisoning in New Caledonia. Both patients died after showing gastro-intestinal symptoms, major bradycardia with marked low blood pressure, and finally asystolia. Both had significative hyperkaliemia, suggesting a digitaline-like substance intoxication. Traditional knowledge in the Loyalty Islands relates coconut crab toxicity to the consumption of the Cerbera manghas fruit by the crustacean. Elsewhere previous descriptions of human poisoning with the kernel of fruits of trees belonging to the genus Cerbera, known to contain cardiotoxic cardenolides, appear to be very similar to our cases. Cardenolides assays were performed on patient's serum samples, fruit kernel and on the crustacean guts, which lead us to suppose these two fatal cases were the result of a neriifolin intoxication, this toxin having been transmitted through the coconut crab.

  5. Benthic infaunal community structuring in an acidified tropical estuarine system

    PubMed Central

    2014-01-01

    Background Recent studies suggest that increasing ocean acidification (OA) should have strong direct and indirect influences on marine invertebrates. While most theory and application for OA is based on relatively physically-stable oceanic ecological systems, less is known about the effects of acidification on nearshore and estuarine systems. Here, we investigated the structuring of a benthic infaunal community in a tropical estuarine system, along a steep salinity and pH gradient, arising largely from acid-sulphate groundwater inflows (Sungai Brunei Estuary, Borneo, July 2011- June 2012). Results Preliminary data indicate that sediment pore-water salinity (range: 8.07 - 29.6 psu) declined towards the mainland in correspondence with the above-sediment estuarine water salinity (range: 3.58 – 31.2 psu), whereas the pore-water pH (range: 6.47- 7.72) was generally lower and less variable than the estuarine water pH (range: 5.78- 8.3), along the estuary. Of the thirty six species (taxa) recorded, the polychaetes Neanthes sp., Onuphis conchylega, Nereididae sp. and the amphipod Corophiidae sp., were numerically dominant. Calcified microcrustaceans (e.g., Cyclopoida sp. and Corophiidae sp.) were abundant at all stations and there was no clear distinction in distribution pattern along the estuarine between calcified and non-calcified groups. Species richness increased seawards, though abundance (density) showed no distinct directional trend. Diversity indices were generally positively correlated (Spearman’s rank correlation) with salinity and pH (p <0.05) and negatively with clay and organic matter, except for evenness values (p >0.05). Three faunistic assemblages were distinguished: (1) nereid-cyclopoid-sabellid, (2) corophiid-capitellid and (3) onuphid- nereid-capitellid. These respectively associated with lower salinity/pH and a muddy bottom, low salinity/pH and a sandy bottom, and high salinity/pH and a sandy bottom. However, CCA suggested that species distribution

  6. Associational resistance protects mangrove leaves from crab herbivory

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Klaassen, Marcel; Ens, Bruno J.

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

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

    PubMed Central

    Okazaki, Robert K.; Wehrtmann, Ingo S.

    2014-01-01

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

  9. Nematodes Infect, But Do Not Manipulate Digging By, Sand Crabs, Lepidopa benedicti

    PubMed Central

    Joseph, Meera; Faulkes, Zen

    2014-01-01

    We examined sand crabs (Lepidopa benedicti) for endoparasites, and found the only parasite consistently infecting the studied population were small nematodes. Because many nematodes have complex life cycles involving multiple hosts, often strongly manipulating their hosts, we hypothesized that nematodes alter the behavior of their sand crab hosts. We predicted that more heavily infected crabs would spend more time above sand than less heavily infected crabs. Our data indicate infection by nematodes was not correlated with duration of time crabs spent above sand. We also suggest that organisms living in sandy beaches may benefit from relatively low parasite loads due to the low diversity of species in the habitat. PMID:24916475

  10. Observations of Crab Nebula and pulsar with VERITAS

    NASA Astrophysics Data System (ADS)

    Celik, Ozlem

    The Crab Nebula, the standard candle in very-high-energy (VHE) astronomy, is one of the most studied sources in all of astronomy. It is scientifically important to measure the energy spectrum of the Crab Nebula close to the inverse Compton peak or above 10 TeV where a deviation from the power law, seen at energies between 300 GeV and ˜5 TeV, may occur. Additionally, it is important to search for pulsed emission from the Crab Pulsar at energies beyond 10 GeV which is the upper limit of the EGRET detection of pulsed emission. Since current models predict a cut-off in the pulsed emission between 10 and 100 GeV, measurements at energies close to this range may help to discriminate between them. With these motivations, the Crab has been observed during the 2-, 3-, and 4-telescope phases of the commissioning of the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The energy spectrum of the Crab Nebula between 350 GeV and 6 TeV is constructed from these data sets. A simple power law, dNdE = (3.19 +/- 0.07stat +/- 0.70 sys) x 10-7 E1TeV 2.40+/-0.03 stat+/-0.17sys TeV-1m-2s-1 , is found to give the best fit to the data obtained with the full 4-telescope array of VERITAS. Furthermore, a periodic modulation is searched for in the gamma-ray emission above 100 GeV at the Crab Pulsar period of 33 ms. The Crab data set from the 2006--2008 VERITAS observations did not show any significant pulsed excess, so an upper limit on the pulsed emission from the Crab Pulsar is obtained. This upper limit constrains the cutoff energy of the spectrum to be less than 50 GeV, assuming that the differential energy spectrum of the pulsed emission has an exponential cutoff.

  11. Ultraviolet Imaging Telescope observations of the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Hennessy, Gregory S.; O'Connell, Robert W.; Cheng, Kwang P.; Bohlin, Ralph C.; Collins, Nicholas R.; Gull, Theodore P.; Hintzen, Paul; Isensee, Joan E.; Landsman, Wayne B.; Roberts, Morton S.

    1992-01-01

    We obtained ultraviolet images of the Crab Nebula with the Ultraviolet Imaging Telescope during the Astro-1 Space Shuttle mission in 1990 December. The UV continuum morphology of the Crab is generally similar to that in the optical region, but the wispy structures are less conspicuous in the UV and X-ray. UV line emission from the thermal filaments is not strong. UV spectral index maps with a resolution of 10 arcsecs show a significant gradient across the nebula, with the outer parts being redder, as expected from synchrotron losses. The location of the bluest synchrotron continuum does not coincide with the pulsar.

  12. Ultraviolet Imaging Telescope observations of the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Hennessy, Gregory S.; O'Connell, Robert W.; Cheng, Kwang P.; Bohlin, Ralph C.; Collins, Nicholas R.; Gull, Theodore R.; Hintzen, Paul; Isensee, Joan E.; Landsman, Wayne B.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.; Stecher, Theodore P.

    1992-08-01

    We obtained ultraviolet images of the Crab Nebula with the Ultraviolet Imaging Telescope during the Astro-1 Space Shuttle mission in 1990 December. The UV continuum morphology of the Crab is generally similar to that in the optical region, but the wispy structures are less conspicuous in the UV and X-ray. UV line emission from the thermal filaments is not strong. UV spectral index maps with a resolution of 10 arcsecs show a significant gradient across the nebula, with the outer parts being redder, as expected from synchrotron losses. The location of the bluest synchrotron continuum does not coincide with the pulsar.

  13. Species Diversity and Abundance of Marine Crabs (Portunidae: Decapoda) from a Collapsible Crab Trap Fishery at Kung Krabaen Bay, Chanthaburi Province, Thailand

    PubMed Central

    Kunsook, Chutapa; Dumrongrojwatthana, Pongchai

    2017-01-01

    The diversity and abundance of marine crabs from a collapsible crab trap fishery at Kung Krabaen Bay, Gulf of Thailand, were observed from August 2012 to June 2013 using 10 sampling stations. The results showed that there were seven families, 11 genera and 17 species (two anomuran and 15 brachyuran crabs). The two anomuran species were Clibanarius virescens (1,710 individuals) and Clibanarius infraspinatus (558 individuals). For brachyuran crabs, Portunidae was the most common family, including 10 species. The dominant species of brachyuran crabs included Thalamita crenata (897 individuals), Portunus pelagicus (806 individuals), Charybdis affinis (344 individuals), Scylla sp. (201 individuals), and Charybdis anisodon (100 individuals). The abundance of crabs was affected by the habitat type. Anomuran crabs had the highest abundance in Halodule pinifolia seagrass beds, whilst brachyurans had the highest abundance in Enhalus acoroides seagrass beds. The dominant brachyuran species were found in pelagic areas near the bay mouth, such as P. pelagicus, P. sanguinolentus, C. feriatus, C. helleri, C. natator, C. affinis, and M. hardwickii. Lastly, reforested mangroves were important habitats for Scylla tranquebarica and C. anisodon. Seasonal and physical factors influenced the abundance of some crabs, for example, the abundance of C. virescens was correlated with temperature, and the abundance of T. crenata was correlated with transparency depth. Our results revealed that Kung Krabaen Bay serves as the home to many marine crab species; however, our results also revealed that 49% of the harvested crabs (2,308 out of 4,694 individuals) were simply discarded and subsequently died. Moreover, our research noted that eight non-target species will become target species in the near future. Therefore, research on the reproductive biology of some marine crabs and an improved understanding of the importance of marine crabs by local fishermen are necessary to prevent biodiversity

  14. Species Diversity and Abundance of Marine Crabs (Portunidae: Decapoda) from a Collapsible Crab Trap Fishery at Kung Krabaen Bay, Chanthaburi Province, Thailand.

    PubMed

    Kunsook, Chutapa; Dumrongrojwatthana, Pongchai

    2017-01-01

    The diversity and abundance of marine crabs from a collapsible crab trap fishery at Kung Krabaen Bay, Gulf of Thailand, were observed from August 2012 to June 2013 using 10 sampling stations. The results showed that there were seven families, 11 genera and 17 species (two anomuran and 15 brachyuran crabs). The two anomuran species were Clibanarius virescens (1,710 individuals) and Clibanarius infraspinatus (558 individuals). For brachyuran crabs, Portunidae was the most common family, including 10 species. The dominant species of brachyuran crabs included Thalamita crenata (897 individuals), Portunus pelagicus (806 individuals), Charybdis affinis (344 individuals), Scylla sp. (201 individuals), and Charybdis anisodon (100 individuals). The abundance of crabs was affected by the habitat type. Anomuran crabs had the highest abundance in Halodule pinifolia seagrass beds, whilst brachyurans had the highest abundance in Enhalus acoroides seagrass beds. The dominant brachyuran species were found in pelagic areas near the bay mouth, such as P. pelagicus, P. sanguinolentus, C. feriatus, C. helleri, C. natator, C. affinis, and M. hardwickii. Lastly, reforested mangroves were important habitats for Scylla tranquebarica and C. anisodon. Seasonal and physical factors influenced the abundance of some crabs, for example, the abundance of C. virescens was correlated with temperature, and the abundance of T. crenata was correlated with transparency depth. Our results revealed that Kung Krabaen Bay serves as the home to many marine crab species; however, our results also revealed that 49% of the harvested crabs (2,308 out of 4,694 individuals) were simply discarded and subsequently died. Moreover, our research noted that eight non-target species will become target species in the near future. Therefore, research on the reproductive biology of some marine crabs and an improved understanding of the importance of marine crabs by local fishermen are necessary to prevent biodiversity

  15. The complete mitogenome of the hydrothermal vent crab Xenograpsus testudinatus (Decapoda, Brachyura) and comparison with brachyuran crabs.

    PubMed

    Ki, Jang-Seu; Dahms, Hans-Uwe; Hwang, Jiang-Shiou; Lee, Jae-Seong

    2009-12-01

    In this study, we analyzed the complete mitochondrial (mt) genome of a hydrothermal vent crab Xenograpsus testudinatus (Decapoda: Brachyura) obtained from the hydrothermal vents off Kueishantao Island, Taiwan, which extend from the deep sea Okinawa Trench. The mitogenome of X. testudinatus was 15,796 bp in length and contained the same 37 genes (e.g. 2 rRNAs, 22 tRNAs, and 13 PCGs) found in other metazoan mitogenomes. Analysis of the structural mt gene order in X. testudinatus revealed that the 13 PCGs, excluding a translocation of ND6-Cyt b cluster, were similarly ordered when compared to the pancrustacean ground pattern; however the tRNAs were severely rearranged. Phylogenetic analysis of decapod mitogenomes showed that the molecular taxonomy of the vent crab was in accordance with its morphological systematics. Together, these findings suggest that the vent crab studied here has little mitochondrial genetic variation when compared with morphologically defined conspecifics from other marine habitats.

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

    PubMed

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

    2016-08-01

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

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

    PubMed

    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.

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

    PubMed Central

    Karplus, Ilan; Achituv, Yair

    2017-01-01

    Crabs of the genus Lybia have the remarkable habit of holding a sea anemone in each of their claws. This partnership appears to be obligate, at least on the part of the crab. The present study focuses on Lybia leptochelis from the Red Sea holding anemones of the genus Alicia (family Aliciidae). These anemones have not been found free living, only in association with L. leptochelis. In an attempt to understand how the crabs acquire them, we conducted a series of behavioral experiments and molecular analyses. Laboratory observations showed that the removal of one anemone from a crab induces a “splitting” behavior, whereby the crab tears the remaining anemone into two similar parts, resulting in a complete anemone in each claw after regeneration. Furthermore, when two crabs, one holding anemones and one lacking them, are confronted, the crabs fight, almost always leading to the “theft” of a complete anemone or anemone fragment by the crab without them. Following this, crabs “split” their lone anemone into two. Individuals of Alicia sp. removed from freshly collected L. leptochelis were used for DNA analysis. By employing AFLP (Fluorescence Amplified Fragments Length Polymorphism) it was shown that each pair of anemones from a given crab is genetically identical. Furthermore, there is genetic identity between most pairs of anemone held by different crabs, with the others showing slight genetic differences. This is a unique case in which one animal induces asexual reproduction of another, consequently also affecting its genetic diversity. PMID:28168117

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

    PubMed

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

    2017-01-01

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

  20. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  1. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  2. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  3. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  4. 50 CFR Table 8 to Part 680 - Initial QS and PQS Pool for Each Crab QS Fishery

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 200,000,000 PIK Pribilof Islands red and blue king crab 30,000,000 30,000,000 SMB St. Matthew blue... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Initial QS and PQS Pool for Each Crab QS... Crab QS Fishery Crab QS Fishery Initial QS Pool Initial PQS Pool BBR Bristol Bay red king crab...

  5. Competition drives clumpy species coexistence in estuarine phytoplankton.

    PubMed

    Segura, A M; Kruk, C; Calliari, D; García-Rodriguez, F; Conde, D; Widdicombe, C E; Fort, H

    2013-01-01

    Understanding the mechanisms that maintain biodiversity is a fundamental problem in ecology. Competition is thought to reduce diversity, but hundreds of microbial aquatic primary producers species coexist and compete for a few essential resources (e.g., nutrients and light). Here, we show that resource competition is a plausible mechanism for explaining clumpy distribution on individual species volume (a proxy for the niche) of estuarine phytoplankton communities ranging from North America to South America and Europe, supporting the Emergent Neutrality hypothesis. Furthermore, such a clumpy distribution was also observed throughout the Holocene in diatoms from a sediment core. A Lotka-Volterra competition model predicted position in the niche axis and functional affiliation of dominant species within and among clumps. Results support the coexistence of functionally equivalent species in ecosystems and indicate that resource competition may be a key process to shape the size structure of estuarine phytoplankton, which in turn drives ecosystem functioning.

  6. Recent developments in three-dimensional numerical estuarine models

    USGS Publications Warehouse

    Cheng, Ralph T.; Smith, Peter E.; Casulli, Vincenzo

    1993-01-01

    For a fixed cost, computing power increases 5 to 10 times every five years. The readily available computing resources have inspired new modal formulations and innovative model applications. Significant progress has been advanced in three-dimensional numerical estuarine modeling within the past three or four years. This paper attempts to review and summarize properties of new 3-D estuarine hydrodynamic models. The emphasis of the review is placed on the formulation, numerical methods. The emphasis of the review is placed on the formulation, numerical methods, spatial and temporal resolution, computational efficiency, and turbulence closure of new models. Recent research has provided guidelines for the proper use of 3-D models involving in the σ-transformation. Other models resort to a fixed level discretization in the vertical. The semi-implicit treatment in time-stepping models appears to have gained momentum. Future research in three-dimensional numerical modeling remains to be on computational efficiency and turbulent closure.

  7. Coevolution of hydraulic, soil and vegetation processes in estuarine wetlands

    NASA Astrophysics Data System (ADS)

    Trivisonno, Franco; Rodriguez, Jose F.; Riccardi, Gerardo; Saco, Patricia; Stenta, Hernan

    2014-05-01

    Estuarine wetlands of south eastern Australia, typically display a vegetation zonation with a sequence mudflats - mangrove forest - saltmarsh plains from the seaward margin and up the topographic gradient. Estuarine wetlands are among the most productive ecosystems in the world, providing unique habitats for fish and many terrestrial species. They also have a carbon sequestration capacity that surpasess terrestrial forest. Estuarine wetlands respond to sea-level rise by vertical accretion and horizontal landward migration, in order to maintain their position in the tidal frame. In situations in which buffer areas for landward migration are not available, saltmarsh can be lost due to mangrove encroachment. As a result of mangrove invasion associated in part with raising estuary water levels and urbanisation, coastal saltmarsh in parts of south-eastern Australia has been declared an endangered ecological community. Predicting estuarine wetlands response to sea-level rise requires modelling the coevolving dynamics of water flow, soil and vegetation. This paper presents preliminary results of our recently developed numerical model for wetland dynamics in wetlands of the Hunter estuary of NSW. The model simulates continuous tidal inflow into the wetland, and accounts for the effect of varying vegetation types on flow resistance. Coevolution effects appear as vegetation types are updated based on their preference to prevailing hydrodynamic conditions. The model also considers that accretion values vary with vegetation type. Simulations are driven using local information collected over several years, which includes estuary water levels, accretion rates, soil carbon content, flow resistance and vegetation preference to hydraulic conditions. Model results predict further saltmarsh loss under current conditions of moderate increase of estuary water levels.

  8. Progress and challenges in coupled hydrodynamic-ecological estuarine modeling

    PubMed Central

    Ganju, Neil K.; Brush, Mark J.; Rashleigh, Brenda; Aretxabaleta, Alfredo L.; del Barrio, Pilar; Grear, Jason S.; Harris, Lora A.; Lake, Samuel J.; McCardell, Grant; O’Donnell, James; Ralston, David K.; Signell, Richard P.; Testa, Jeremy M.; Vaudrey, Jamie M.P.

    2016-01-01

    Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational power, and incorporation of uncertainty. Coupled hydrodynamic-ecological models have been used to assess ecosystem processes and interactions, simulate future scenarios, and evaluate remedial actions in response to eutrophication, habitat loss, and freshwater diversion. The need to couple hydrodynamic and ecological models to address research and management questions is clear, because dynamic feedbacks between biotic and physical processes are critical interactions within ecosystems. In this review we present historical and modern perspectives on estuarine hydrodynamic and ecological modeling, consider model limitations, and address aspects of model linkage, skill assessment, and complexity. We discuss the balance between spatial and temporal resolution and present examples using different spatiotemporal scales. Finally, we recommend future lines of inquiry, approaches to balance complexity and uncertainty, and model transparency and utility. It is idealistic to think we can pursue a “theory of everything” for estuarine models, but recent advances suggest that models for both scientific investigations and management applications will continue to improve in terms of realism, precision, and accuracy. PMID:27721675

  9. Managing bay and estuarine ecosystems for multiple services

    USGS Publications Warehouse

    Needles, Lisa A.; Lester, Sarah E.; Ambrose, Richard; Andren, Anders; Beyeler, Marc; Connor, Michael S.; Eckman, James E.; Costa-Pierce, Barry A.; Gaines, Steven D.; Lafferty, Kevin D.; Lenihan, Junter S.; Parrish, Julia; Peterson, Mark S.; Scaroni, Amy E.; Weis, Judith S.; Wendt, Dean E.

    2013-01-01

    Managers are moving from a model of managing individual sectors, human activities, or ecosystem services to an ecosystem-based management (EBM) approach which attempts to balance the range of services provided by ecosystems. Applying EBM is often difficult due to inherent tradeoffs in managing for different services. This challenge particularly holds for estuarine systems, which have been heavily altered in most regions and are often subject to intense management interventions. Estuarine managers can often choose among a range of management tactics to enhance a particular service; although some management actions will result in strong tradeoffs, others may enhance multiple services simultaneously. Management of estuarine ecosystems could be improved by distinguishing between optimal management actions for enhancing multiple services and those that have severe tradeoffs. This requires a framework that evaluates tradeoff scenarios and identifies management actions likely to benefit multiple services. We created a management action-services matrix as a first step towards assessing tradeoffs and providing managers with a decision support tool. We found that management actions that restored or enhanced natural vegetation (e.g., salt marsh and mangroves) and some shellfish (particularly oysters and oyster reef habitat) benefited multiple services. In contrast, management actions such as desalination, salt pond creation, sand mining, and large container shipping had large net negative effects on several of the other services considered in the matrix. Our framework provides resource managers a simple way to inform EBM decisions and can also be used as a first step in more sophisticated approaches that model service delivery.

  10. The Distribution of Thermophilic Sulfate-reducing Bacteria Along an Estuarine Gradient Reveals Multiple Origins of Endospores in Estuarine Sediments

    NASA Astrophysics Data System (ADS)

    Bell, E.

    2015-12-01

    Cold marine sediments harbour inactive spores of thermophilic bacteria. These misplaced thermophiles are genetically similar to microorganisms detected in deep biosphere environments, leading to the hypothesis that seabed fluid flow transports thermophiles out of warm subsurface environments and into the ocean. Estuaries form the transition between the marine and the terrestrial biosphere and are influenced by tidal currents, surface run-off and groundwater seepage. Endospores from thermophilic bacteria present in estuarine sediments could therefore originate from a number of sources that may influence the estuary differently. We have therefore tested the hypothesis that this will lead to a gradient in the composition of thermophilic endospore populations in estuarine sediments. The distribution of thermophilic spore-forming sulfate-reducing bacteria along an estuarine gradient from freshwater (River Tyne, UK) to marine (North Sea) was investigated. Microbial community analysis by 16S rRNA gene amplicon sequencing revealed changes in the thermophilic population enriched at different locations within the estuary. Certain species were only detected at the marine end, highlighting possible links to deep marine biosphere habitats such as oil reservoirs that harbour closely related Desulfotomaculum spp. Conversely, other taxa were predominantly observed in the freshwater reaches of the estuary indicating dispersal from an upstream or terrestrial source. Different endospore populations were enriched dependent on incubation temperature and spore heat-resistance. Microcosms incubated at 50, 60 or 70°C showed a shift in the dominant species of Desulfotomaculum enriched as the temperature increased. Microcosms triple-autoclaved at 121°C prior to incubation still showed rapid and reproducible sulfate-reduction and some Desulfotomaculum spp. remained active after autoclaving at 130°C. These results show that temperature physiology and biogeographic patterns can be used to

  11. 50 CFR 253.30 - Crab IFQ loans.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... crab fishing vessel; (2) Who has been issued the appropriate documentation of eligibility by RAM; (3... credit enhancement. (g) Crew member transfer eligibility certification. The Program will accept RAM... of any person determined by RAM to be unable to receive such certification will be...

  12. 50 CFR 253.30 - Crab IFQ loans.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... crab fishing vessel; (2) Who has been issued the appropriate documentation of eligibility by RAM; (3... credit enhancement. (g) Crew member transfer eligibility certification. The Program will accept RAM... of any person determined by RAM to be unable to receive such certification will be...

  13. 50 CFR 253.30 - Crab IFQ loans.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... crab fishing vessel; (2) Who has been issued the appropriate documentation of eligibility by RAM; (3... credit enhancement. (g) Crew member transfer eligibility certification. The Program will accept RAM... of any person determined by RAM to be unable to receive such certification will be...

  14. 50 CFR 253.30 - Crab IFQ loans.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... crab fishing vessel; (2) Who has been issued the appropriate documentation of eligibility by RAM; (3... credit enhancement. (g) Crew member transfer eligibility certification. The Program will accept RAM... of any person determined by RAM to be unable to receive such certification will be...

  15. A Toll-like receptor in horseshoe crabs.

    PubMed

    Inamori, Kei-ichiro; Ariki, Shigeru; Kawabata, Shun-ichiro

    2004-04-01

    Non-self-recognition of invading microbes relies on the pattern-recognition of pathogen-associated molecular patterns (PAMPs) derived from microbial cell-wall components. Insects and mammals conserve a signaling pathway of the innate immune system through cell-surface receptors called Tolls and Toll-like receptors (TLRs). Bacterial lipopolysaccharides (LPSs) are an important trigger of the horseshoe crab's innate immunity to infectious microorganisms. Horseshoe crabs' granular hemocytes respond specifically to LPS stimulation, inducing the secretion of various defense molecules from the granular hemocytes. Here, we show a cDNA which we named tToll, coding for a TLR identified from hemocytes of the horseshoe crab Tachypleus tridentatus. tToll is most closely related to Drosophila Toll in both domain architecture and overall length. Human TLRs have been suggested to contain numerous PAMP-binding insertions located in the leucine-rich repeats (LRRs) of their ectodomains. However, the LRRs of tToll contained no obvious PAMP-binding insertions. Furthermore, tToll was non-specifically expressed in horseshoe crab tissues. These observations suggest that tToll does not function as an LPS receptor on granular hemocytes.

  16. Early drawings of Messier 1: pineapple or crab?

    NASA Astrophysics Data System (ADS)

    Dewhirst, D. W.

    1983-06-01

    Articles on the history of the Crab Nebula frequently reproduce an enigmatical drawing of it by Lord Rosse. This drawing was quickly repudiated by him and replaced by a more recognizable one which is less well known. Both drawings are discussed.

  17. 50 CFR Table 4 to Part 680 - Crab Process Codes

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Crab Process Codes 4 Table 4 to Part 680... Frozen. 3 Salted/brined. 6 Cooked. 7 Live. 18 Fresh/vacuum pack. 21 Frozen/block. 22 Frozen/shatter pack. 28 Frozen/vacuum pack....

  18. 50 CFR Table 4 to Part 680 - Crab Process Codes

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Crab Process Codes 4 Table 4 to Part 680... Frozen. 3 Salted/brined. 6 Cooked. 7 Live. 18 Fresh/vacuum pack. 21 Frozen/block. 22 Frozen/shatter pack. 28 Frozen/vacuum pack....

  19. 50 CFR 680.6 - Crab economic data report (EDR).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... fishing year being reported, record insurance premiums (for hull, property and indemnity, and pollution.... (vi) BSAI crab-specific vessel costs. Insurance premiums (hull, property and indemnity, and pollution...: CR fishery code; dates covered (beginning and ending day, month and year); number of days at...

  20. 50 CFR 680.6 - Crab economic data report (EDR).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... fishing year being reported, record insurance premiums (for hull, property and indemnity, and pollution.... (vi) BSAI crab-specific vessel costs. Insurance premiums (hull, property and indemnity, and pollution...: CR fishery code; dates covered (beginning and ending day, month and year); number of days at...

  1. Hard X-ray Variations in the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.; Cherry, M. L.; Case, G. L.; Baumgarter, W. H.; Beklen, E.; Bhat, P. N.; Briggs, M. S.; Camero-Arranz, A.; Chaplin, V.; Connaughton, V.; Finger, M. H.; Gehrels, N.; Greiner, J.; Jahoda, K.; Jenke, P.; Kippen, R. M.; Kouveliotou, C.; Krimm, H. A.; Kuulkers, E.; Lund, N.; Meegan, C. A.; Natalucci, L.; Paciesas, W. S.; Preece, R.; Rodi, J. C.

    2012-01-01

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

  2. Crab Nebula Variations in Hard X-rays

    NASA Technical Reports Server (NTRS)

    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

  3. Hard X-ray Variations in the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.; Cherry, M. L.; Case, G. L.; Baumgartner, W. H.; Beklen, E.; Bhat, P. N.; Briggs, M. S.; Camero-Arranz, A.; Chaplin, V.; Connaughton, V.; Finger, M. H.; Gehrels, N.; Greiner, J.; Jahoda, K.; Jenke, P.; Kippen, R. M.; Kouveliotou, C.; Krimm, H. A.; Kuulkers, E.; Meegan, C. A.; Natalucci, L.; Paciesas, W. S.; Preece, R.; Rodi, J. C.; Skinner, G. K.

    2013-01-01

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

  4. Hard X-ray Variations in the Crab Nebula

    NASA Technical Reports Server (NTRS)

    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.; Gehrels, N.; Greiner, J.; Jahoda, K.; Jenke, P.; Kippen, R. M.; Kouveliotou, C.; Krimm, H. A.; Kuulkers, E.; Meegan, C. A.; Natalucci, L.; Paciesas, W. S.; Preece, R.; Rodi, J. C.; Skinner, G. K.

    2013-01-01

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

  5. X-ray observations of Crab-like supernova remnants

    NASA Technical Reports Server (NTRS)

    Becker, R. H.

    1983-01-01

    Distinguishing radio and morphological characteristics of Crab Nebula-like supernova remnants (SNR) are described. Radio features comprise a flat spectrum, a filled center brightness distribution, and a centrally located pulsar. The radio signals are linearly polarized and suggest a synchrotron emission mechanism. Known objects with those characteristics include the Crab Nebula, Vela X, 3C58, G21.5 - 0.9 and G74.9 + 1.2. Only the Crab Nebula exhibits pulsations, while all have unresolved X-ray sources and nonthermal X-ray spectra. Although the Crab-like SNR are distinctly different from shell-like SNR, the SNR CTB80, G326.3 - 1.8, W28 and G29.7 0.3 display characteristics of both, particularly shell-like structures and flat spectra. X-ray spectra from compact sources have also been detected from 3C58, CTB80, W28 and MSH 15 - 52 and exhibit nonthermal power law features. The X-ray spectra could be used as a measure of the evolutionary stage of the source.

  6. Classroom Applications Using Limulus Polyphemus--The American Horseshoe Crab.

    ERIC Educational Resources Information Center

    Pearson, Frederick C., III; Weary, Marlys

    1981-01-01

    Provides examples of several classroom activities utilizing the American horseshoe crab (Limulus Polyphemus), including raising fertilized eggs, fertilizing eggs in vitro, and testing water samples. Includes background information on the natural history, life cycle, and breeding habits of this animal. (DS)

  7. Damping of unwanted modes in SRF deflecting/crabbing cavities

    SciTech Connect

    Burt, Graeme; Wang, Haipeng

    2014-01-01

    As deflecting and crab cavities do not use the fundamental acceleration mode for their operation, the spectrum of unwanted modes is significantly different from that of accelerating cavities. The fundamental acceleration mode is now unwanted and can cause energy spread in the beam; in addition this mode frequency is often close to or lower than that of the deflecting mode, making it difficult to damp. This is made more complex in some of the compact crab cavities as there small beampipes often attenuate the fields very sharply. In addition in some crab cavities there can be an orthogonal transverse mode similar to the deflecting mode, known as the same order mode. The degeneracy of these modes must be split by polarising the cavity and if the polarisation is not large enough, dampers should be placed at either an electric or magnetic field null of the crabbing mode to effectively damp the unwanted polarisation. Various concepts for dealing with unwanted modes in various SRF deflecting cavities will be reviewed.

  8. Characteristics of Yeasts Isolated from Pacific Crab Meat

    PubMed Central

    Eklund, M. W.; Spinelli, J.; Miyauchi, D.; Groninger, H.

    1965-01-01

    A total of 202 cultures of yeasts were isolated and characterized from king crab and Dungeness crab meat. A yeastlike organism, resembling Aureobasidium pullulans, and 15 different species distributed among the genera Rhodotorula, Cryptococcus, Torulopsis, Candida, and Trichosporon were represented. Nine of the species grew at 5 C or lower. Although two of the species grew at 37 C, none of the isolates had the characteristics of pathogenic species. Members of the Cryptococcus and Candida failed to grow at 37 C. Furthermore, species of the former genus were not pathogenic to mice. The pigmentation of the Rhodotorula cultures decreased in intensity as the incubation temperature was decreased. Biochemical activities of the different species were studied by use of triglycerides, lecithin, and proteins (casein, gelatin, and crab-meat protein) as substrates. Eight of the species could attack triglycerides; eight, lecithin; five, gelatin; one, casein; and one, crab protein. An organism, tentatively identified as Trichosporon sp., was very active in attacking each of the substrates tested and grew well at 0.5 C. PMID:5866045

  9. Aggression and Food Resource Competition between Sympatric Hermit Crab Species

    PubMed Central

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

    2014-01-01

    The vertical zonation patterns of intertidal organisms have been topics of interest to marine ecologists for many years, with interspecific food competition being implicated as a contributing factor to intertidal community organization. In this study, we used behavioral bioassays to examine the potential roles that interspecific aggression and food competition have on the structuring of intertidal hermit crab assemblages. We studied two ecologically similar, sympatric hermit crab species, Clibanarius digueti [1] and Paguristes perrieri [2], which occupy adjacent zones within the intertidal region of the Gulf of California. During the search phase of foraging, C. digueti showed higher frequencies of aggressive behaviors than P. perrieri. In competition assays, C. digueti gained increased access to food resources compared to P. perrieri. The results suggest that food competition may play an important role in structuring intertidal hermit crab assemblages, and that the zonation patterns of Gulf of California hermit crab species may be the result of geographical displacement by the dominant food competitor (C. digueti). PMID:24632897

  10. Aerobic response to exercise of the fastest land crab.

    PubMed

    Full, R J; Herreid, C F

    1983-04-01

    To view the aerobic response to exercise, the ghost crab Ocypode guadichaudii was run in a treadmill respirometer at three velocities (0.13, 0.19, and 0.28 km/h) while oxygen consumption (VO2) was monitored. A steady-state VO2 that increased linearly with velocity was attained. VO2 transient periods at the beginning and end of exercise were extremely rapid with half times from 50 to 150 s. The magnitude of oxygen deficit and debt were small and both showed increases with an increase in velocity. Oxygen debt was measured at each velocity after 4-, 10-, and 20-min exercise bouts. No change in the magnitude of oxygen debt was observed with respect to exercise duration. Maximal VO2 was 11.9 times the average resting VO2. Oxygen uptake kinetics have shown only very sluggish and reduced rates in five other more sedentary crab species previously tested. The aerobic response pattern observed in the present study is more comparable to that of exercising mammals and highly aerobic ectothermic vertebrates. This suggests that the ghost crab meets the energy demand of sustained exercise by aerobic ATP production in contrast to many other crab species.

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

    ERIC Educational Resources Information Center

    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…

  12. Use of Terrestrial Hermit Crabs in the Study of Habituation

    ERIC Educational Resources Information Center

    Nolan, Laurence J.

    2004-01-01

    For small colleges, the use of invertebrates in undergraduate learning laboratory experiments may be a valuable alternative to the use of vertebrate species. This article describes a habituation experiment using terrestrial hermit crabs. All of the materials required are inexpensive and readily available. What makes this experiment unique is that…

  13. X-ray Pulsar in the Crab Nebula.

    PubMed

    Fritz, G; Henry, R C; Meekins, J F; Chubb, T A; Friedman, H

    1969-05-09

    X-ray pulsations have been observed in the Crab Nebula at a frequency closely matching the radio and optical pulsations. About 5 percent of the total x-ray power of the nebula appears in the pulsed component. The x-ray pulsations have the form of a main pulse and an interpulse separated by about 12 milliseconds.

  14. Three-Dimensional Concentration Measurements around Actively Tracking Blue Crabs

    NASA Astrophysics Data System (ADS)

    Dickman, B. D.; Jackson, J. L.; Weissburg, M. J.; Webster, D. R.

    2006-11-01

    Many aquatic arthropods locate food, suitable habitats, and mates solely through information extracted by chemical signals in their environment. Chemical plumes detected by larger animals are influenced by turbulence that creates an intermittent and unpredictable chemical stimulus environment. To link the stimulus pattern to behavior, we have developed a measurement system to quantify the instantaneous odor concentration surrounding a freely tracking blue crab through three-dimensional laser-induced fluorescence (3DLIF). A blue crab receives chemical stimulus at several locations, including the antennules near the mouth region and the distal tips of the legs and claws. Hence, three-dimensional measurements of the concentration field are required to link behavior to plume structure. During trials, crabs began their search 150 cm downstream of a source, and walking kinematics were recording simultaneously. The crabs were reversibly ``blindfolded'' during tracking to prevent aversive reactions to the intense laser light. Our experiments allow us to examine how hypothesized navigational cues, such as concentration bursts at the antennules and spatial asymmetry in concentration at the distributed chemosensory organs on the legs and claws, results in particular decisions during navigation.

  15. Space Movie Reveals Shocking Secrets Of The Crab Pulsa

    NASA Astrophysics Data System (ADS)

    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

  16. Signals from 'crabworld': cuticular reflections in a fiddler crab colony.

    PubMed

    Zeil, J; Hofmann, M

    2001-07-01

    Fiddler crabs inhabit intertidal sand- and mudflats, where they live in dense colonies and are active on the surface during low tide. They exhibit a rich behavioural repertoire, with frequent interactions between animals in the context of territorial and mating activities. Male fiddler crabs have one massively enlarged and conspicuously coloured claw, which they use in waving displays and in fights with other males. The crabs carry their eyes on long, vertically oriented stalks high above the body and, as a consequence, see the bodies of conspecifics in the ventral visual field, below the local visual horizon, and against the mudflat surface as background. We filmed events in a colony of Uca vomeris with a normal video camera and an ultraviolet-sensitive camera placed at the eye height of an average crab, approximately 2-3 cm above ground. We also used a spectrographic imager and linear polarized filters to analyse the cues potentially available to the animals for detecting, monitoring and possibly identifying each other. Areas of high contrast in mudflat scenes include specular reflections on the wet cuticle of crabs that are horizontally polarised. Besides specular reflections, some parts of the cuticle generate high-contrast signals against the mudflat background, both at wavelengths between 400 and 700 nm, and in the ultraviolet region between 300 and 400 nm. Uca vomeris can be very colourful: the different parts of the large claw of the male are white, orange or red. The carapace colours of both males and females can range from a mottled yellowish green brown, to a brilliant light blue. White and blue colours contrast starkly with the mudflat background, especially in the ultraviolet wavelengths. Under stress, the blue and white colours can change within minutes to a duller and darker blue or to a dull white.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Density affects mating mode and large male mating advantage in a fiddler crab.

    PubMed

    Ribeiro, Pablo D; Daleo, Pedro; Iribarne, Oscar O

    2010-12-01

    Fiddler crabs show two different mating modes: either females search and crabs mate underground in male burrows, or males search and crabs mate on the surface near female burrows. We explored the relationship between crab density, body size, the searching behavior of both sexes, and the occurrence of both mating modes in the fiddler crab Uca uruguayensis. We found that crabs change their mating mode depending on their size and crab density. Crabs mated mostly on the surface at low densities, and underground at high densities. The proportion of wandering receptive females but not courting males accounted for the variation in mating modes. This suggests that whether crabs mate underground (or on the surface) is determined by the presence (or absence) of searching females. We found that the change in the mating mode affected the level of assortative mating; males mating underground were bigger than those mating on the surface, suggesting active female choice. Given that fiddler crabs experience multiple reproductive cycles, they are prone to showing behavioral plasticity in their mating strategy whenever the payoffs of using different mating modes differ between reproductive events. Our results suggest that the incorporation of different levels of environmental variability may be important in theoretical models aimed at improving our understanding of the evolution of alternative mating tactics and strategies.

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

    SciTech Connect

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

    2002-12-01

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

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

    PubMed

    Vicente, Vania A; Orélis-Ribeiro, R; Najafzadeh, M J; Sun, Jiufeng; Guerra, Raquel Schier; Miesch, Stephanie; Ostrensky, Antonio; Meis, Jacques F; Klaassen, Corné H; de Hoog, G S; Boeger, Walter A

    2012-07-06

    Lethargic Crab Disease (LCD) caused extensive epizootic mortality of the mangrove land crab Ucides cordatus (Brachyura: Ocypodidae) along the Brazilian coast, mainly in the Northeastern region. The disease was named after the symptoms of slow movement of infected crabs. Causative agents were suspected to be two black yeast-like fungi of the family Herpotrichiellaceae (ascomycete order Chaetothyriales), judged by infected tissue biopsies from moribund U. cordatus. The aim of the present study is to prove that two species are involved in the disease: the recently described black yeast Exophiala cancerae, but also a less virulent, hitherto undescribed fonsecaea-like species, introduced here as the novel species Fonsecaea brasiliensis. Strains were identified by ITS rDNA sequencing, and species borderlines were established by multilocus sequencing and AFLP analysis. Fonsecaea brasiliensis proved to be closely related to the pathogenic species Cladophialophora devriesii which originally was isolated from a systemic infection in a human patient. The virulence of F. brasiliensis is lower than that of E. cancerae, as established by artificial inoculation of mangrove crabs.

  1. ASSESSMENT OF RISK REDUCTION STRATEGIES FOR THE MANAGEMENT OF AGRICULTURAL NONPOINT SOURCE PESTICIDE RUNOFF IN ESTUARINE ECOSYSTEMS

    EPA Science Inventory

    Agricultural nonpoint source (NPS) runoff may result in significant discharges of pesticides, suspended sediments, and fertilizers into estuarine habitats adjacent to agricultural areas or downstream from agricultural watersheds. Exposure of estuarine fin fish and shellfish to to...

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

    PubMed

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

    2012-04-01

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

  3. 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

    EPA Science Inventory

    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...

  4. Relative toxicity of spent lubricant oil and detergent against benthic macro-invertebrates of a west African estuarine lagoon.

    PubMed

    Chukwu, L O; Odunzeh, C C

    2006-07-01

    The relative acute toxicity of spent lubricant oil and detergent was evaluated against hermit crab, Clibanarius africanus (Aurivillus) and periwinkle, Tympanotonus fuscatus (L) from the Lagos lagoon in laboratory bioassays. Based on the derived toxicity indices, the detergent (96 hr LC50 = 5.77ml/l) was found to be 1.73 times more toxic than spent engine oil (96 hr LC50 = 10.01 ml/l) when acting singly against C africanus and 18.73 times (96 hr LC50-48.67 ml/l) more toxic (96 hr LC50 = 911.57 ml/l) when acting singly against T. fuscatus. On the basis of the computed susceptibility factors, C. africanus was found to be about eight times and ninety-one times more susceptible to the toxic effect of detergent and spent lubricant oil respectively. The randomized analysis of variance (ANOVA) showed that there was significant difference (Fcal 58.83 Ftab 3.87; DF 13; p > 0.05) between all treatments of spent lubricant oil and detergent during the 96 hr exposure period of test animals. At 5% level of significance the Student Neuman-Keuls (SNK) test further revealed significant differences in the mean mortality response of test animals exposed to toxicants at all concentrations and untreated control. The results obtained in this study suggest that the estuarine benthic macroinvertebrates, which play key roles in the environment, may serve as useful in-situ sentinels for biomonitoring studies of petroleum pollutants in fragile aquatic ecosystems such as the Lagos lagoon.

  5. Identification of trophic interactions within an estuarine food web (northern New Zealand) using fatty acid biomarkers and stable isotopes

    NASA Astrophysics Data System (ADS)

    Alfaro, Andrea C.; Thomas, François; Sergent, Luce; Duxbury, Mark

    2006-10-01

    Fatty acid biomarkers and stable isotope signatures were used to identify the trophic dynamics of a mangrove/seagrass estuarine food web at Matapouri, northern New Zealand. Specific fatty acids were used to identify the preferred food sources (i.e., mangroves, seagrass, phytoplankton, macroalgae, bacteria, and zooplankton) of dominant fauna (i.e., filter feeders, grazing snails, scavenger/predatory snails, shrimp, crabs, and fish), and their presence in water and sediment samples throughout the estuary. The diets of filter feeders were found to be dominated by dinoflagellates, whereas grazers showed a higher diatom contribution. Bacteria associated with organic debris on surface sediments and brown algal ( Hormosira banksii) material in the form of suspended organic matter also accounted for a high proportion of most animal diets. Animals within higher trophic levels had diverse fatty acid profiles, revealing their varied feeding strategies and carbon sources. The stable isotope (δ 13C and δ 15N) analyses of major primary producers and consumers/predators revealed a trend of 15N enrichment with increasing trophic level, while δ 13C values provided a generally good description of carbon flow through the food web. Overall results from both fatty acid profiles and stable isotopes indicate that a variety of carbon sources with a range of trophic pathways typify this food web. Moreover, none of the animals studied was dependent on a single food source. This study is the first to use a comprehensive fatty acid biomarker and stable isotope approach to investigate the food web dynamics within a New Zealand temperate mangrove/seagrass estuary. This quantitative research may contribute to the currently developing management strategies for estuaries in northern New Zealand, especially for those perceived to have expanding mangrove fringes.

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

    NASA Astrophysics Data System (ADS)

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

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

  7. 77 FR 65533 - Proposed Information Collection; Comment Request; National Estuarine Research Reserve System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-29

    ... Estuarine Research Reserve System Science Collaborative Evaluation AGENCY: National Oceanic and Atmospheric... Estuarine Research Reserve System (NERRS) Science Collaborative was created in 2009 to put Reserve-based... intended users of the science into the research process so that their perspectives can inform...

  8. THE PACIFIC COAST ESTUARINE INFORMATION SYSTEM: CREATING A BASELINE FOR THE FUTURE

    EPA Science Inventory

    Coastal researchers and managers have a growing need for ready access to a diversity of
    data types, including estuarine-specific lists of native and nonindigenous species and estuarine/landscape characteristics. These data are key components in ecological risk assessments in g...

  9. AN EVALUATION OF ELECTRODE INSERTION TECHNIQUES FOR MEASUREMENT OF REDOX POTENTIAL IN ESTUARINE SEDIMENTS

    EPA Science Inventory

    Eh measurements by electrodes are commonly used to characterize redox status of sediments in freshwater, marine and estuarine studies, due to the relative ease and rapidity of data collection. In our studies of fine-grained estuarine seabeds, we observed that Eh values measured i...

  10. 15 CFR 921.30 - Designation of National Estuarine Research Reserves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... AND COASTAL RESOURCE MANAGEMENT NATIONAL ESTUARINE RESEARCH RESERVE SYSTEM REGULATIONS Reserve... representative estuarine ecosystem that is suitable for long-term research and contributes to the biogeographical... agencies and/or private organizations) have been signed; and (7) The coastal state in which the area...

  11. BOOK REVIEW: ESTUARINE SCIENCE: A SYNTHETIC APPROACH TO RESEARCH AND PRACTICE

    EPA Science Inventory

    This book is the product of fifty leading estuarine scientists most of whom attended a workshop convened for the purpose of "put[ting] together the case for synthesis of estuarine data and to show the capabilities of synthetic methods of research" (p. 2). The editor, John E. Hob...

  12. 15 CFR 921.52 - Promotion and coordination of estuarine research.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 3 2010-01-01 2010-01-01 false Promotion and coordination of estuarine research. 921.52 Section 921.52 Commerce and Foreign Trade Regulations Relating to Commerce and... Research Projects § 921.52 Promotion and coordination of estuarine research. (a) NOAA will promote...

  13. 75 FR 67950 - Notice of Designation of the Lake Superior National Estuarine Research Reserve in Wisconsin

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-04

    ... of Designation of the Lake Superior National Estuarine Research Reserve in Wisconsin AGENCY: Estuarine Reserves Division, Office of Ocean and Coastal Resource Management, National Ocean Service... certain lands and waters of the St. Louis River freshwater estuary in Wisconsin as the Lake...

  14. 15 CFR 921.52 - Promotion and coordination of estuarine research.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Research Projects § 921.52 Promotion and coordination of estuarine research. (a) NOAA will promote and coordinate the use of the National Estuarine Research Reserve System for research purposes. (b) NOAA will, in...) NOAA will consult with other Federal and state agencies to promote use of one or more research...

  15. 15 CFR 921.52 - Promotion and coordination of estuarine research.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Research Projects § 921.52 Promotion and coordination of estuarine research. (a) NOAA will promote and coordinate the use of the National Estuarine Research Reserve System for research purposes. (b) NOAA will, in...) NOAA will consult with other Federal and state agencies to promote use of one or more research...

  16. 15 CFR 921.52 - Promotion and coordination of estuarine research.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Research Projects § 921.52 Promotion and coordination of estuarine research. (a) NOAA will promote and coordinate the use of the National Estuarine Research Reserve System for research purposes. (b) NOAA will, in...) NOAA will consult with other Federal and state agencies to promote use of one or more research...

  17. 15 CFR 921.52 - Promotion and coordination of estuarine research.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Research Projects § 921.52 Promotion and coordination of estuarine research. (a) NOAA will promote and coordinate the use of the National Estuarine Research Reserve System for research purposes. (b) NOAA will, in...) NOAA will consult with other Federal and state agencies to promote use of one or more research...

  18. Metals in horseshoe crab eggs from Delaware Bay, USA: temporal patterns from 1993 to 2012.

    PubMed

    Burger, Joanna; Tsipoura, Nellie

    2014-10-01

    The health of horseshoe crab (Limulus polyphemus) eggs is important not only to maintain horseshoe crab populations, but because they are a resource for higher trophic levels, such as fish and shorebirds. We examined the concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the eggs of horseshoe crabs from Delaware Bay (between New Jersey and Delaware, USA) in 1993, 1994, 1995, 1999, 2000, and 2012 to determine if there were significant temporal changes and if levels appear to pose a health risk to the crabs themselves, or to predators that consume them. All metal levels declined in horseshoe crab eggs between 1994 and 2012, although the declines were much less consistent for lead and chromium than that for mercury and cadmium. Levels of contaminants found in these eggs are well below those known to cause adverse effects in the crabs themselves or to organisms that consume them, such as migrating shorebirds.

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

    PubMed

    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.

  20. Toxicity of the dispersant Corexit 9500 to early life stages of blue crab, Callinectes sapidus.

    PubMed

    Anderson Lively, Julie A; McKenzie, Jon

    2014-12-01

    The Deepwater Horizon well released 4.4 million barrels of light crude oil offshore of Louisiana into one of the world's largest and most productive blue crab (Callinectes sapidus) fisheries. The objectives of this paper were to determine the toxicity of the dispersant Corexit(®) 9500A used in the 2010 oil spill on juvenile and larval blue crabs, and the long-term effects of sublethal acute exposure. Only the highest treatment levels of dispersant significantly increased mortality in larval and juvenile blue crabs (100 mg/L and 1,000 mg/L, respectively). This correlated to concentrations well above levels found in the Gulf of Mexico following the spill. Smaller and younger crabs showed higher mortality than older and larger crabs. This research indicates direct application of dispersants on crab larvae could cause acute mortality, but dilution through diffusion and natural weathering processes would minimize long-term effects.

  1. Disease, parasite, and commensal prevalences for blue crab Callinectes sapidus at shedding facilities in Louisiana, USA.

    PubMed

    Rogers, Holly A; Taylor, Sabrina S; Hawke, John P; Schott, Eric J; Anderson Lively, Julie A

    2015-01-15

    Blue crab diseases, parasites, and commensals are not well studied in the Gulf of Mexico, and their prevalence rates have only been sporadically determined. Commercial soft shell shedding facilities in Louisiana experience high mortality rates of pre-molt crabs, and some of these deaths may be attributable to diseases or parasites. During the active shedding season in 2013, we determined the prevalence of shell disease, Vibrio spp., Lagenophrys callinectes, and Hematodinium perezi at 4 commercial shedding facilities along the Louisiana coast. We also detected Ameson michaelis and reo-like virus infections. Shell disease was moderately prevalent at rates above 50% and varied by shedding facility, collection month, and crab size. Vibrio spp. bacteria were prevalent in the hemolymph of 37% of the pre-molt crabs. Lagenophrys callinectes was highly prevalent in the pre-molt crabs, but because it is a commensal species, it may not cause high mortality rates. Hematodinium perezi was absent in all pre-molt crabs.

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

    USGS Publications Warehouse

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

    2013-01-01

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

  3. OSSE observations of the Crab pulsar

    NASA Technical Reports Server (NTRS)

    Ulmer, M. P.; Lomatch, S.; Matz, S. M.; Grabelsky, D. A.; Purcell, W. R.; Grove, J. E.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.

    1994-01-01

    We present results of the Compton Gamma-Ray Observatory (CGRO) Oriented Scintillation Spectrometer Experiment (OSSE) observations of the Crab pulsar, made during MJD 48373-48406 (1991 April 27 - 1991 May 30) and MJD 48798-48804 (1992 June 25 - 1992 July 1). Pulsar light curves and spectra over the approximately 0.05 to 10 MeV range are presented. The arrival time of the gamma-ray peak and the radio peak agree to within 30 microsec which is better than the approximately 300 microsec accuracy of the measurements. The overall pulse phase averaged spectrum in the 0.1 - 10 MeV range is well-fit by a power law of the form 0.05 x (E/0.13 MeV)exp(-(1.99 +/- 0.03)) photons/sq cm/s. The outer-gap model (with gap parameter equal to 0.46) provided to us by Ho agrees with the data to better than 20%. The spectra of the bridge and second peak are slightly harder than the first peak as measured by the hardness ratio (approximately 110 - 220 keV)/(approximately 50 - 105 keV): P1 = 0.54 +/- 0.01, P2 = 0.63 +/- 0.01, bridge = 0.68 +/- 0.03. The phase of the two peaks in the light curve is constant over the 50 - 550 keV range to within the accuracy of the measurements (better than 0.02 in phase). No evidence was found for variability of the light curve on timescales from 2 minutes (less than a factor of 1.8) to 1 year (less than a factor of 1.06), where these are 3 sigma upper limits. However, when we examine the historical database, we find, in agreement with Nolan et al. (1993), that there is evidence for a 13 year variation in the ratio of the intensity of peak 2 to peak 1. We show that if this is interpreted as being due to precession (which changes the relative view of the intrinsic gamma-ray pulse as seen on earth), the variation is consistent with models of neutron star structure. The optical data may be in conflict with the interpretation however. We found no statistically significant lines in the 50 - 550 keV range in the spectrum. The average 3 sigma upper limits in 10(exp

  4. Turing Patterns in Estuarine Sediments by Microbiological Activity

    NASA Astrophysics Data System (ADS)

    De Morais Mendonca Teles, Antonio

    2016-07-01

    The use of Turing mechanisms and lattice Lotka-Volterra model (LLV), also by means of the non-extensive statistical mechanics, can mathematically describe well the phenomena of clustering and their associated boundaries with fractal dimensionality, which occurs in various natural situations, among them, biogeochemical processes via microorganisms in estuarine and marine sediments on the planet Earth. The author did an experimental analysis in field work which took into account the spatial and temporal behavior of Turing patterns, in the form of microbial activity within estuarine subsurface sediments. We show we can find the characteristics of clustering and fractallity which are present in the dynamical LLV model and Turing patterns mechanisms, and the non-extensive statistical mechanics could be used to find the q-entropy (Sq), and other non-equilibrium statistical parameters of the studied estuarine (Caraís lagoon) subsurface biogeochemical system. In this paper, the author suggests that such kinds of subsurface ecological systems are of interest to Astrobiology because if we find Turing-type clustered geomorphological patterns, below meter scale, on the near subsurface and inside rocks at the surface of planet Mars, and also find non-equilibrium statistical parameters (temperature, [F], [C], [S], etc.), displaying Turing-type mechanism, in the aquatic environments of the internal seas of planets Jupiter's moon Europa and the internal global ocean of Saturn's moon Enceladus, that could mean that possible hypothetical biogeochemical activities are present in such places. This could be a bio-indicator tool. And with further studies we could find the q-entropy Sq to establish better defined statistical mechanical parameters for such environments and to refine models for their evolution, as we do on planet Earth.

  5. Transport of persistent organic pollutants by microplastics in estuarine conditions

    NASA Astrophysics Data System (ADS)

    Bakir, Adil; Rowland, Steven J.; Thompson, Richard C.

    2014-03-01

    Microplastics represent an increasing source of anthropogenic contamination in aquatic environments, where they may also act as scavengers and transporters of persistent organic pollutants. As estuaries are amongst the most productive aquatic systems, it is important to understand sorption behaviour and transport of persistent organic pollutants (POPs) by microplastics along estuarine gradients. The effects of salinity sorption equilibrium kinetics on the distribution coefficients (Kd) of phenanthrene (Phe) and 4,4‧-DDT, onto polyvinyl chloride (PVC) and onto polyethylene (PE) were therefore investigated. A salinity gradient representing freshwater, estuarine and marine conditions, with salinities corresponding to 0 (MilliQ water, 690 μS/cm), 8.8, 17.5, 26.3 and 35 was used. Salinity had no significant effect on the time required to reach equilibrium onto PVC or PE and neither did it affect desorption rates of contaminants from plastics. Although salinity had no effect on sorption capacity of Phe onto plastics, a slight decrease in sorption capacity was observed for DDT with salinity. Salinity had little effect on sorption behaviour and POP/plastic combination was shown to be a more important factor. Transport of Phe and DDT from riverine to brackish and marine waters by plastic is therefore likely to be much more dependent on the aqueous POP concentration than on salinity. The physical characteristics of the polymer and local environmental conditions (e.g. plastic density, particle residence time in estuaries) will affect the physical transport of contaminated plastics. A transport model of POPs by microplastics under estuarine conditions is proposed. Transport of Phe and DDT by PVC and PE from fresh and brackish water toward fully marine conditions was the most likely net direction for contaminant transport and followed the order: Phe-PE >> DDT-PVC = DDT-PE >> Phe-PVC.

  6. Fluvio-estuarine sedimentation and estuarine evolution during the Late-Holocene in the Taw Estuary, England: response to relative sea-level and climate change

    NASA Astrophysics Data System (ADS)

    Havelock, G. M.; Brown, T. G.

    2010-12-01

    Present models of Holocene estuary evolution are driven largely by changes in relative sea-level (RSL) with little reference to long-term changes in fluvial regime and regional climate. Centennial-scale climate change has been shown to have a major control on Holocene river behaviour, with fluvial records showing evidence for a high sensitivity of flood occurrence to changing climate. It follows that the changes in river discharge associated with these climatic fluctuations should have an important bearing on inner estuarine hydrology and sedimentology. Indeed, recent US studies have shown that changes in freshwater inflow can be inferred by changes in estuarine paleosalinity and that the timing of these events reflect changes in regional precipitation. Deposition in the transitional inner estuarine environment can therefore be seen to be controlled by both marine and fluvial influences. The fluvio-estuarine late-Holocene sedimentary record was investigated in the macro-tidal Taw Estuary, south-west England in order to ascertain the relative importance of changes in RSL and precipitation driven river discharge on estuarine sedimentation and centennial-scale geomorphic evolution. The inner estuarine record was compared with a local RSL reconstruction for the Taw Estuary and with a reconstructed Holocene flood record and geomorphic fluvial history for the lower Taw valley. The diatom record of numerous sediment cores enabled paleosalinity to be evaluated. The fluvio-estuarine valley fill was split into a series of stratigraphic units, with a chronological framework derived using radiocarbon and OSL dating methods. Geomorphic change in the inner estuarine zone is shown to be mainly influenced by phases of increased river discharge and catchment precipitation, with fluvial instability translating down river into the inner estuarine system. This results in periods of enhanced tidal channel migration, marsh-floodplain formation and estuarine channel-bed aggradation

  7. Anaerobic oxidation of acetylene by estuarine sediments and enrichment cultures

    USGS Publications Warehouse

    Culbertson, Charles W.; Zehnder, Alexander J. B.; Oremland, Ronald S.

    1981-01-01

    Acetylene disappeared from the gas phase of anaerobically incubated estuarine sediment slurries, and loss was accompanied by increased levels of carbon dioxide. Acetylene loss was inhibited by chloramphenicol, air, and autoclaving. Addition of 14C2H2 to slurries resulted in the formation of 14CO2 and the transient appearance of 14C-soluble intermediates, of which acetate was a major component. Acetylene oxidation stimulated sulfate reduction; however, sulfate reduction was not required for the loss of C2H2 to occur. Enrichment cultures were obtained which grew anaerobically at the expense of C2H2.

  8. Anaerobic Oxidation of Acetylene by Estuarine Sediments and Enrichment Cultures

    PubMed Central

    Culbertson, Charles W.; Zehnder, Alexander J. B.; Oremland, Ronald S.

    1981-01-01

    Acetylene disappeared from the gas phase of anaerobically incubated estuarine sediment slurries, and loss was accompanied by increased levels of carbon dioxide. Acetylene loss was inhibited by chloramphenicol, air, and autoclaving. Addition of 14C2H2 to slurries resulted in the formation of 14CO2 and the transient appearance of 14C-soluble intermediates, of which acetate was a major component. Acetylene oxidation stimulated sulfate reduction; however, sulfate reduction was not required for the loss of C2H2 to occur. Enrichment cultures were obtained which grew anaerobically at the expense of C2H2. PMID:16345714

  9. Fractional-step method for two-dimensional estuarine transport

    USGS Publications Warehouse

    Bales, Jerad D.; Holley, Edward R.

    1988-01-01

    The fractional-step method was used in this study to split the longitudinal advective transport term from the other terms in the two-dimensional, laterally-averaged equation for estuarine mass transport. The method of characteristics with spline interpolations was used to approximate the longitudinal advective transport. A general discussion of the fractional-step method, the specific algorithm developed in this investigation, and results of numerical tests are presented. Application of the fractional-step method in conjunction with the characteristic-spline scheme offers the potential for improved simulations of transport for situations in which concentration gradients are steep.

  10. Estuarine density fronts and their effect on oil slicks

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator); Polis, D. F.; Davis, G. R.

    1976-01-01

    The author has identified the following significant results. Estuarine fronts represent regions of extremely high gradient or discontinuity in various parameters of physical interest, the most important being the water velocity and density fields. Aircraft and boats were combined to study the behavior of different types of fronts in Delaware Bay and their effect on pollutants in order to provide a basis for improving an oil drift and spreading model. Imagery from the LANDSAT satellites provided the most effective means of determining the location and extent of frontal systems over all portions of the tidal cycle. This data is being used to modify the oil drift and spreading model.

  11. Estimating Dungeness crab (Cancer magister) abundance: Crab pots and dive transects compared

    USGS Publications Warehouse

    Taggart, S. James; O'Clair, Charles E.; Shirley, Thomas C.; Mondragon, Jennifer

    2004-01-01

    Dungeness crabs (Cancer magister) were sampled with commercial pots and counted by scuba divers on benthic transects at eight sites near Glacier Bay, Alaska. Catch per unit of effort (CPUE) from pots was compared to the density estimates from dives to evaluate the bias and power of the two techniques. Yearly sampling was conducted in two seasons: April and September, from 1992 to 2000. Male CPUE estimates from pots were significantly lower in April than in the following September; a step-wise regression demonstrated that season accounted for more of the variation in male CPUE than did temperature. In both April and September, pot sampling was significantly biased against females. When females were categorized as ovigerous and nonovigerous, it was clear that ovigerous females accounted for the majority of the bias because pots were not biased against nonovigerous females. We compared the power of pots and dive transects in detecting trends in populations and found that pots had much higher power than dive transects. Despite their low power, the dive transects were very useful for detecting bias in our pot sampling and in identifying the optimal times of year to sample so that pot bias could be avoided.

  12. Ontogeny of salinity tolerance and hyper-osmoregulation by embryos of the intertidal crabs Hemigrapsus edwardsii and Hemigrapsus crenulatus (Decapoda, Grapsidae): survival of acute hyposaline exposure.

    PubMed

    Taylor, H H; Seneviratna, Deepani

    2005-04-01

    The adults of Hemigrapsus edwardsii and Hemigrapsus crenulatus are euryhaline crabs and strong hyper-osmoregulators. Their embryos are carried externally attached to the abdominal pleopods of female crabs, where they are exposed to temporal and spatial changes in salinity associated with their intertidal and estuarine habitats. Although embryos lack the branchial and excretory organs responsible for adult osmoregulation, post-gastrula embryos were highly tolerant of exposure to hypo-osmotic sea water. Detached eggs (embryos+envelopes), of both species, at all developmental stages between gastrulation and hatching, exhibited 80-100% survival for periods up to 96 h in sea water (osmolality, 1050 mmol kg(-1)) and in dilutions to 50%, 10%, and 1%. Cleavage stages were less tolerant of dilution; H. edwardsii, <50% survived 24 h in 10% sea water; H. crenulatus <50% survived 6 h in 10% sea water. Post-gastrulation stages strongly hyper-osmoregulated but cleavage stages were hyper-osmoconformers (maintaining internal osmolality approximately 150 mmol kg(-1) above external). Osmoregulatory capacity was reduced just prior hatching, particularly in H. crenulatus, although salinity tolerance remained high. Gastrulation therefore marks a critical stage in the ontogeny of osmoregulation and salinity tolerance. Total Na+/K(+)-ATPase activity increased greatly during embryogenesis of H. crenulatus (undetectable in blastulae; gastrulae 0.31+/-0.05 pmol P(i) embryo(-1) min(-1); pre-hatching 16.4+/-1.0 pmol P(i) embryo(-1) min(-1)). Na+/K(+)-ATPase activity increased in embryos exposed to dilute sea water for 24 h implicating regulation of this transporter in a short-term acclimation response.

  13. Influence of salinity on the larval development of the fiddler crab Uca vocator (Ocypodidae) as an indicator of ontogenetic migration towards offshore waters

    NASA Astrophysics Data System (ADS)

    de Jesus de Brito Simith, Darlan; de Souza, Adelson Silva; Maciel, Cristiana Ramalho; Abrunhosa, Fernando Araújo; Diele, Karen

    2012-03-01

    Larvae of many marine decapod crustaceans are released in unpredictable habitats with strong salinity fluctuations during the breeding season. In an experimental laboratory study, we investigated the influence of seven different salinities (0, 5, 10, 15, 20, 25 and 30) on the survival and development time of fiddler crab zoea larvae, Uca vocator, from northern Brazilian mangroves. The species reproduces during the rainy season when estuarine salinity strongly fluctuates and often reaches values below 10 and even 5. Salinity significantly affected the survival rate and development period from hatching to megalopa, while the number of zoeal stages remained constant. In salinities 0 and 5, no larvae reached the second zoeal stage, but they managed to survive for up to 3 (average of 2.3 days) and 7 days (average of 5.1 days), respectively. From salinity 10 onwards, the larvae developed to the megalopal stage. However, the survival rate was significantly lower (5-15%) and development took more time (average of 13.5 days) in salinity 10 than in the remaining salinities (15-30). In the latter, survival ranged from 80-95% and development took 10-11 days. Given the 100% larval mortality in extremely low salinities and their increased survival in intermediate and higher salinities, we conclude that U. vocator has a larval `export' strategy with its larvae developing in offshore waters where salinity conditions are more stable and higher than in mangrove estuaries. Thus, by means of ontogenetic migration, osmotic stress and resulting mortality in estuarine waters can be avoided.

  14. Bacteria associated with crabs from cold waters with emphasis on the occurrence of potential human pathogens.

    PubMed Central

    Faghri, M A; Pennington, C L; Cronholm, L S; Atlas, R M

    1984-01-01

    A diverse array of bacterial species, including several potential human pathogens, was isolated from edible crabs collected in cold waters. Crabs collected near Kodiak Island, Alaska, contained higher levels of bacteria than crabs collected away from regions of human habitation. The bacteria associated with the crabs collected near Kodiak included Yersinia enterocolitica, Klebsiella pneumoniae, and coagulase-negative Staphylococcus species; the pathogenicity of these isolates was demonstrated in mice. Although coliforms were not found, the bacterial species associated with the tissues of crabs collected near Kodiak indicate possible fecal contamination that may have occurred through contact with sewage. Compared with surrounding waters and sediments, the crab tissues contained much higher proportions of gram-positive cocci. As revealed by indirect plate counts and direct scanning electron microscopic observations, muscle and hemolymph tissues contained much lower levels of bacteria than shell and gill tissues. After the death of a crab, however, the numbers of bacteria associated with hemolymph and muscle tissues increased significantly. Microcosm studies showed that certain bacterial populations, e.g., Vibrio cholerae, can be bioaccumulated in crab gill tissues. The results of this study indicate the need for careful review of waste disposal practices where edible crabs may be contaminated with microorganisms that are potential human pathogens and the need for surveillance of shellfish for pathogenic microorganisms that naturally occur in marine ecosystems. Images PMID:6742824

  15. Crabs Mediate Interactions between Native and Invasive Salt Marsh Plants: A Mesocosm Study

    PubMed Central

    Zhang, Xiao-dong; Jia, Xin; Chen, Yang-yun; Shao, Jun-jiong; Wu, Xin-ru; Shang, Lei; Li, Bo

    2013-01-01

    Soil disturbance has been widely recognized as an important factor influencing the structure and dynamics of plant communities. Although soil reworkers were shown to increase habitat complexity and raise the risk of plant invasion, their role in regulating the interactions between native and invasive species remains unclear. We proposed that crab activities, via improving soil nitrogen availability, may indirectly affect the interactions between invasive Spartina alterniflora and native Phragmites australis and Scirpus mariqueter in salt marsh ecosystems. We conducted a two-year mesocosm experiment consisting of five species combinations, i.e., monocultures of three species and pair-wise mixtures of invasive and native species, with crabs being either present or absent for each combination. We found that crabs could mitigate soil nitrogen depletion in the mesocosm over the two years. Plant performance of all species, at both the ramet-level (height and biomass per ramet) and plot-level (density, total above- and belowground biomass), were promoted by crab activities. These plants responded to crab disturbance primarily by clonal propagation, as plot-level performance was more sensitive to crabs than ramet-level. Moreover, crab activities altered the competition between Spartina and native plants in favor of the former, since Spartina was more promoted than native plants by crab activities. Our results suggested that crab activities may increase the competition ability of Spartina over native Phragmites and Scirpus through alleviating soil nitrogen limitation. PMID:24023926

  16. Multipole Field Effects for the Superconducting Parallel-Bar Deflecting/Crabbing Cavities

    SciTech Connect

    De Silva, Payagalage Subashini Uddika; Delayen, Jean Roger

    2012-09-01

    The superconducting parallel-bar deflecting/crabbing cavity is currently being considered as one of the design options in rf separation for the Jefferson Lab 12 GeV upgrade and for the crabbing cavity for the proposed LHC luminosity upgrade. Knowledge of multipole field effects is important for accurate beam dynamics study of rf structures. The multipole components can be accurately determined numerically using the electromagnetic surface field data in the rf structure. This paper discusses the detailed analysis of those components for the fundamental deflecting/crabbing mode and higher order modes in the parallel-bar deflecting/crabbing cavity.

  17. The Crab nebula and pulsar in the MeV energy range

    NASA Technical Reports Server (NTRS)

    Much, R.; Bennett, K.; Buccheri, R.; Busetta, M.; Diehl, R.; Forrest, D.; Hermsen, W.; Kuiper, L.; Lichti, G. G.; Mcconnell, M.

    1995-01-01

    The imaging Compton Telescope (COMPTEL) is sensitive in the energy range of 0.75 to 30 MeV. COMPTEL observed the Crab several times during the Compton Gamma Ray Observatory (CGRO) sky survey and CGRO Phase II. Both the Crab pulsar and nebula are detected over the entire COMPTEL energy range. The phase-averaged energy spectra of the Crab Pulsar and Nebula are presented. The combined observations provide sufficient statistics for a phase-resolved analysis of the Crab pulsar spectrum.

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

    USGS Publications Warehouse

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

    1998-01-01

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

  19. Spatial patterns and movements of red king and Tanner crabs: Implications for the design of marine protected areas

    USGS Publications Warehouse

    Taggart, S.J.; Mondragon, Jennifer; Andrews, A.G.; Nielsen, J.K.

    2008-01-01

    Most examples of positive population responses to marine protected areas (MPAs) have been documented for tropical reef species with very small home ranges; the utility of MPAs for commercially harvested temperate species that have large movement patterns remains poorly tested. We measured the distribution and abundance of red king Paralithodes camtschaticus and Tanner Chionoecetes bairdi crabs inside and outside of MPAs in Glacier Bay National Park, Alaska, USA. By tagging a sub-sample of crabs with sonic tags, we estimated the movement of adult crabs from one of the MPAs (Muir Inlet) into the central portion of Glacier Bay where fishing still occurs. Tanner crabs and red king crabs moved similar average distances per day, although Tanner crabs had a higher transfer out of the Muir Inlet MPA into the central bay. Tanner crab movements were characterized by large variation among individual crabs, both in distance and direction traveled, while red king crabs migrated seasonally between 2 specific areas. Although Tanner crabs exhibited relatively large movements, distribution and abundance data suggest that they may be restricted at large spatial scales by habitat barriers. MPAs that are effective at protecting king and especially Tanner crab brood stock from fishing mortality will likely need to be larger than is typical of MPAs worldwide. However, by incorporating information on the seasonal movements of red king crabs and the location of habitat barriers for Tanner crabs, MPAs could likely be designed that would effectively protect adults from fishing mortality. ?? Inter-Research 2008.

  20. Zoothamnium duplicatum infestation of cultured horseshoe crabs (Limulus polyphemus).

    PubMed

    Shinn, Andrew P; Mühlhölzl, Alexander P; Coates, Christopher J; Metochis, Christoforos; Freeman, Mark A

    2015-02-01

    An outbreak of the sessile peritrich Zoothamnium duplicatum in a pilot, commercial-scale Limulus polyphemus hatchery resulted in the loss of ∼96% (40,000) second/third instar larvae over a 61day period. peritrich growth was heavy, leading to mechanical obstruction of the gills and physical damage. The peritrichs were controlled without resultant loss of juvenile crabs by administering 10ppm chlorine in freshwater for 1h and the addition of aquarium grade sand; a medium into which the crabs could burrow and facilitate cleaning of the carapace. Peritrich identity was confirmed from a partial SSU rDNA contiguous sequence of 1343bp (99.7% similarity to Z. duplicatum).