Meso- and bathy-pelagic fish parasites at the Mid-Atlantic Ridge (MAR): Low host specificity and restricted parasite diversity     

Sven Klimpel  Markus Wilhelm Busch  Tracey Sutton  Harry Wilhelm Palm 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(4):596-603

Seven meso- and bathy-pelagic fish species from the Mid-Atlantic Ridge (MAR) were firstly studied for fish parasites and feeding ecology. With a total of seven parasite species, the 247 meso- and bathy-pelagic deep-sea fish specimens belonging to the families Melamphaidae (3 spp.), Myctophidae (3 spp.) and Stomiidae (1 sp.) revealed low parasite diversity. The genetically identified nematodes Anisakis simplex (s.s.) and Anisakis pegreffii from the body cavity, liver and muscles of Myctophum punctatum were the most abundant parasites, reaching a prevalence of 91.4% and mean intensity of 3.1 (1–14). Anisakis sp. (unidentified) infected Chauliodus sloani and Poromitra crassiceps. Bothriocephalidean and tetraphyllidean cestode larvae infected Benthosema glaciale, the latter also occurring in C. sloani and Scopelogadus beanii, at low prevalences. Adult parasites at low infection rates included the digenean Lethadena sp. (2.9%), and the two copepod species Sarcotretes scopeli (5.7%) and Tautochondria dolichoura (5.3–11.4%). The myctophid Lampanyctus macdonaldi and the melamphaid Scopelogadus mizolepis mizolepis were free of parasites. Analyses of the stomach contents revealed crustaceans, especially copepods and euphausiids for the myctophids and also amphipods for the melamphaids as predominant prey items. While all stomachs showing distinct content comprising often unidentified ‘tissue’ (possibly gelatinous zooplankton), only C. sloani preyed upon fish. Though this feeding habit would enable transfer of a variety of crustacean-transmitted parasites into the fish, the parasite fauna in the meso- and bathy-pelagic fish was species poor. All observed parasites showed low host specificity, demonstrating no distinct pattern of host–parasite co-evolution. The MAR is no barrier for the parasite distribution in the North Atlantic meso- and bathy-pelagial.  相似文献   

The assessment of vitellogenin as a biomarker of exposure to estrogenic compounds in two Australian perciformes   总被引：1，自引：0，他引：1  

Codi King S  Hassell K  Nugegoda D  Kristiansen SI 《Marine environmental research》2008,66(1):116-118

Vitellogenin (Vtg) is a yolk protein precursor that has been identified as a sensitive biomarker for exposure to estrogenic compounds. We evaluated specific monoclonal and polyclonal antibodies for reactivity with plasma Vtg from two Australian Perciformes, the tropical barramundi (Lates calcarifer) and the temperate black bream (Acanthopagrus butcheri). Blood plasma from 17beta-estradiol exposed (E2) male barramundi (20 mg kg(-1)) and male black bream (2.5-5.0 mg kg(-1)) were sent to Biosense Laboratories (Norway) for cross-reactivity testing using their extensive anti-Vtg antibody selection. Indirect ELISA results determined barramundi plasma displayed the highest binding affinities to ND-3G2 (monoclonal-Mab) and PO-1 (polyclonal-Pab). Black bream was most cross-reactive with ND-1C8 (Mab) and PO-2 (Pab). Next, plasma was assessed for Vtg induction in E2-dosed (5 mg kg(-1)), hatchery-reared barramundi and black bream versus a non-injected control group. Vtg production was assessed by Western blot and indirect ELISA using ND-3G2 and ND-1C8 Mabs, respectively. A prominent band was identified in the range of 100-200 kDa for all female black bream and for all E2-treated barramundi and black bream males, which was confirmed as Vtg by Western blot. Indirect ELISA results for barramundi demonstrated highly significant differences in E2-dosed fish as compared to control fish (Student t, P<0.001). E2 male black bream were significantly different than control males (Student t, P<0.001) and control and E2 females displayed highly significant differences (Student t, P<0.001). These results indicate that exposure to 17beta-estradiol induces significant Vtg production in males of the two Australian Perciformes, with potential use as a biomarker for exposure to estrogenic compounds.  相似文献   

Big Earth Data science: an information framework for a sustainable planet     

Huadong Guo  Dong Liang  Max Craglia  Lizhe Wang  Sven Schade 《International Journal of Digital Earth》2020,13(7):743-767

  相似文献   

Geochemical aspects of permeability controlled partial melting and fractional crystallization     

Sven Maaløe 《Geochimica et cosmochimica acta》1982,46(1):43-57

Magma accumulation in the mantle requires that the mantle be permeable. Experimental investigations show that the permeability threshold first will be attained after a certain degree of partial melting. The influence of the permeability threshold on the composition of partial melts is evaluated using the fayalite-forsterite system as an example. In addition the variation in trace element concentrations are calculated for different distribution coefficients. Primary magmas formed by accumulation when a minimal degree of partial melting is required for permeability display a remarkably small variation in composition up to 30% partial melting. It is suggested from REE abundances that primary tholeiitic magmas have been generated by permeability controlled partial melting. The compositions of the primary magmas generated by permeability controlled partial melting will not differ much from the compositions obtained by batch melting, but the degrees of partial melting will differ for similar compositions.  相似文献   

Power and cross-power spectral studies of electric parameters under fair weather conditions in the atmospheric surface layer     

Sven Israelsson  Cornelius Oluwafemi 《Boundary-Layer Meteorology》1975,9(1):21-32

Power spectral and cross-spectral studies of atmospheric electrical parameters for different months of the year are presented. The data represent fair weather conditions and the frequency range is from 0.01 to 0.3 cph. The analysis shows spectral peaks in the atmospheric electric parameters for frequencies corresponding to the diurnal wave; in many cases large variances are noted for the frequencies 0.083, 0.125 and 0.17 cph. Annual cycles in the spectra are also observed. In general, fairly small variances are obtained for frequencies above 0.05 cph. High coherences for the atmospheric electric parameters are observed in the lower frequency part of the spectra and in some cases in other parts as well (i.e., 0.083, 0.125 and 0.17 cph). Phase relationships of the electric components are also presented.  相似文献   

Phase relations in the system NaCl-KCl-H2O II: Differential thermal analysis of the halite liquidus in the NaCl-H2O binary above 450°c     

W.D Gunter  I-Ming Chou  Sven Girsperger 《Geochimica et cosmochimica acta》1983,47(5):863-873

Thermal analysis of the halite liquidus in the system NaCl-H₂O has been conducted for NaCl mole fractions (X_NaCl) greater than 0.25 (i.e., > 50 wt. % NaCl) at pressures between 0.3 and 4.1 kb and temperatures greater than 450°C. The position of the liquidus was located by differential thermal analysis (DTA) of cooling scans only, as heating scans did not produce definitive DTA peaks. The dP/dT slope of the liquidus is positive and steep at high pressures, but at high X_NaCl, and pressures below 0.5 kb it appears to reverse slope and intersects the three-phase curve (liquid-halite-vapour) at a shallow angle. However, due to the complex nature of the DTA signal when P <- 0.5 kb, there is considerable doubt about exactly what event has been recorded in the experiments conducted at these low pressures.The solubility of halite can be expressed as a function of the mole-fractional-based activity of NaCl in the liquid phase (L) in temperature (T, °K) and pressure (P, bars) In $\text{α}{}_{\mathrm{NaCl(L.T.P)}}\text{=}\text{?19.884 ? 0.001275T ? 1388}\text{T + 3.2305 In (T) ? 0.07574PT}$ Our liquidus data (based on 10 compositions) above 500 bars for these brines were combined with this equation to generate activity coefficients of NaCl which were fit within their experimental uncertainties to the following one parameter Margules equation In $\text{γ}{}_{\mathrm{NaCl(L.T.P)}}\text{=}\text{(0.7268 ? 695.7}\text{T ? 0.1217PT)}\text{(1 ? X}{}_{\mathrm{NaCl}}\text{)}{}^2$. Concentrated solutions of NaCl show negative deviations from ideality which rapidly increase in magnitude with decreasing X_NaCl.  相似文献   

Unusual transition in quartzite dislocation creep regimes and crystal slip systems in the aureole of the Eureka Valley–Joshua Flat–Beer Creek pluton, California: a case for anhydrous conditions created by decarbonation reactions     

Sven S. Morgan  Richard D. Law 《Tectonophysics》2004,384(1-4):209-231

Microstructures and quartz c-axis fabrics were analyzed in five quartzite samples collected across the eastern aureole of the Eureka Valley–Joshua Flat–Beer Creek composite pluton. Temperatures of deformation are estimated to be 740±50 °C based on a modified c-axis opening angle thermometer of Kruhl (J. Metamorph. Geol. 16 (1998) 142). In quartzite layers located closest (140 m) to the pluton-wall rock contact, flattened detrital grains are plastically deformed and partially recrystallized. The dominant recrystallization process is subgrain rotation (dislocation creep regime 2 of Hirth and Tullis (J. Struct. Geol. 14 (1992) 145)), although grain boundary migration (dislocation creep regime 3) is also evident. Complete recrystallization occurs in quartzite layers located at a distance of 240 m from the contact, and coincides with recrystallization taking place dominantly through grain boundary migration (regime 3). Within the quartzites, strain is calculated to be lowest in the layers closest to the pluton margin based on the aspect ratios of flattened detrital grains.The c-axis fabrics indicate that a slip operated within the quartzites closest to the pluton-wall rock contact and that with distance from the contact the operative slip systems gradually switch to prism [c] slip. The spatial inversion in microstructures and slip systems (apparent “high temperature” deformation and recrystallization further from the pluton-contact and apparent “low temperature” deformation and recrystallization closer to the pluton-contact) coincides with a change in minor phase mineral content of quartzite samples and also in composition of the surrounding rock units. Marble and calc-silicate assemblages dominate close to the pluton-wall rock contact, whereas mixed quartzite and pelite assemblages are dominant further from the contact.We suggest that a thick marble unit located between the pluton and the quartzite layers acted as a barrier to fluids emanating from the pluton. Decarbonation reactions in marble layers interbedded with the inner aureole quartzites and calc-silicate assemblages in the inner aureole quartzites may have produced high X_CO2 (water absent) fluids during deformation. The presence of high X_CO2 fluid is inferred from the prograde assemblage of quartz+calcite (and not wollastonite)+diopside±K-feldspar in the inner aureole quartzites. We suggest that it was these “dry” conditions that suppressed prism [c] slip and regime 3 recrystallization in the inner aureole and resulted in a slip and regime 2 recrystallization, which would normally be associated with lower deformation temperatures. In contrast, the prograde assemblage in the pelite-dominated outer part of the aureole is biotite+K-feldspar. These “wet” pelitic assemblages indicate fluids dominated by water in the outer part of the aureole and promoted prism [c] slip and regime 3 recrystallization. Because other variables could also have caused the spatial inversion of c-axis fabrics and recrystallization mechanisms, we briefly review those variables known to cause a transition in slip systems and dislocation creep regimes in quartz. Our conclusions are based on a small number of samples, and therefore, the unusual development of crystal fabrics and microstructures in the aureole to the EJB pluton suggests that further study is needed on the effect of fluid composition on crystal slip system activity and recrystallization mechanisms in naturally deformed rocks.  相似文献   

The Triassic Santa Juana Formation at the lower Biobío River, south central Chile     

Sven N. Nielsen 《Journal of South American Earth Sciences》2005,19(4):89

A sequence of Triassic rocks is exposed near the town of Concepción, Chile. These clastic strata are interpreted as the deposits of rivers, lakes, playas, and alluvial fans. The deposits comprise conglomerates, arkosic sandstones, and sand-, silt- and mudstones. Four facies associations comprising eight sedimentary facies can be distinguished. Plant fossils from the sedimentary sequence of the Santa Juana Formation indicate a Carnian age. The flora includes ferns (Gleichenites, Cladophlebis, Dictyophyllum, Thaumatopteris, Asterotheca, Saportaea) and seed ferns (Kurtziana, Antevsia, Dicroidium), ginkgophytes (Sphenobaiera), cycads (Pseudoctenis), conifers (Heidiphyllum, Telemachus, Rissikia), and gymnosperms of uncertain affinities (Linguifolium, Gontriglossa). Two new species are presented: Pseudoctenis santajuanensis and Gontriglossa reinerae.  相似文献   

PGE distribution in massive sulfides from the PACMANUS hydrothermal field, eastern Manus basin, Papua New Guinea: implications for PGE enrichment in some ancient volcanogenic massive sulfide deposits     

Jan Pašava  Anna Vymazalová  Sven Petersen  Peter Herzig 《Mineralium Deposita》2006,41(2):201-202

  相似文献   

Area-Averaged Surface Fluxes Over the Litfass Region Based on Eddy-Covariance Measurements     

Frank Beyrich  Jens-Peter Leps  Matthias Mauder  Jens Bange  Thomas Foken  Sven Huneke  Horst Lohse  Andreas Lüdi  Wouter M. L. Meijninger  Dmitrii Mironov  Ulrich Weisensee  Peter Zittel 《Boundary-Layer Meteorology》2006,121(1):33-65

Micrometeorological measurements (including eddy-covariance measurements of the surface fluxes of sensible and latent heat) were performed during the LITFASS-2003 experiment at 13 field sites over different types of land use (forest, lake, grassland, various agricultural crops) in a 20 × 20 km² area around the Meteorological Observatory Lindenberg (MOL) of the German Meteorological Service (Deutscher Wetterdienst, DWD). Significant differences in the energy fluxes could be found between the major land surface types (forest, farmland, water), but also between the different agricultural crops (cereals, rape, maize). Flux ratios between the different surfaces changed during the course of the experiment as a result of increased water temperature of the lake, changing soil moisture, and of the vegetation development at the farmland sites. The measurements over grass performed at the boundary-layer field site Falkenberg of the MOL were shown to be quite representative for the farmland part of the area. Measurements from the 13 sites were composed into a time series of the area-averaged surface flux by taking into account the data quality of the single flux values from the different sites and the relative occurrence of each surface type in the area. Such composite fluxes could be determined for about 80% of the whole measurement time during the LITFASS-2003 experiment. Comparison of these aggregated surface fluxes with area-averaged fluxes from long-range scintillometer measurements and from airborne measurements showed good agreement.  相似文献