Metazoan parasites in intertidal cockles Cerastoderma edule from the northern Wadden Sea   总被引：2，自引：0，他引：2  

David W. Thieltges  Karsten Reise 《Journal of Sea Research》2006,56(4):284-293

At four intertidal sites near the island of Sylt (eastern North Sea), 13 metazoan parasite taxa were found in 1400 cockles investigated, with digenean trematodes being dominant. Almost all cockles were infected by parasites and most individuals harboured more than one parasite species. We observed four conspicuous patterns: (1) Adult cockles harboured a two times higher species richness (2003: 6.1 ± 0.7 species/host; 2004: 7.1 ± 0.7) than juveniles (2003: 2.9 ± 0.8; 2004: 3.4 ± 0.8) and total parasite community composition significantly differed between age groups. (2) Infection levels were 2–52 times higher in adult cockles than in juveniles both in trematode species and in non-trematode species. In the dominant trematodes, species utilising cockles as first intermediate host (Gymnophallus choledochus, Labratrema minimus, Monorchis parvus) only occurred in adult cockles, and prevalences were low (2–12%). Prevalences of up to 100% were reached by trematodes using cockles as second intermediate host (Himasthla elongata, H. continua, H. interrupta, Renicola roscovita, Psilostomum brevicolle, Meiogymnophallus minutus, Gymnophallus gibberosus). Metacercariae of these species were segregated between body parts within cockles. (3) High spatial heterogeneity in parasite community composition and infection levels occurred between sampling sites. However, communities in juveniles were more similar than communities in adults. (4) Temporal variation in parasite community composition was low between two consecutive years, especially for adult cockles. The omnipresence of parasites in this dominant bivalve species has important implications for sampling designs and as a potentially confounding variable in e.g. physiological studies. It suggests strong and cumulative negative effects on the cockle hosts.  相似文献   

An autoradiographic study of the chlorinated biphenyl, 2,4,5,2′,4′,5′-hexachlorobiphenyl, and the polycyclic aromatic hydrocarbon, phenanthrene, in flounder (platicchthys flesus) accompanied by liquid scintillation counting     

Jan Erik Solbakken  Karsten H. Palmork  Kristian Ingebrigtsen 《Marine environmental research》1984,14(1-4)

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The North-Chilean Coast Range — an example for the development of an active continental margin     

Dr. Karsten Berg  Dr. Christoph Breitkreuz  Dr. Klaus -Werner Damm  Siegfried Pichowiak  Prof. Dr. Werner Zeil 《International Journal of Earth Sciences》1983,72(2):715-731

Analysis of extended plutons in the Coast Range of North Chile between 25°30′ and 26°35′ led to the recognition of a complex magmatic and structural evolution from the Upper Paleozoic to the Tertiary. The ascension of the intrusive bodies is dictated by deep-seated block tectonics. Generally the chemistry changes from S-type magmas in the Paleozoic to I-type magmas in the Mesozoic and Cainozoic. This is accompanied by a change in the structural geology of the continental margin which we present in six hypothetic phases (Devonian-Tertiary). We are only at the beginning of an encompassing synthesis of the genesis of the Andean orogen.  相似文献   

Corrections for near surface effects: Decomposition of the magnetotelluric impedance tensor and scaling corrections for regional resistivities: A tutorial   总被引：1，自引：0，他引：1  

Ross W. Groom  Karsten Bahr 《Surveys in Geophysics》1992,13(4-5):341-379

This paper primarily examines the effects of small-scale or near-surface conductivity inhomogeneities on the magnetotelluric (MT) impedance tensor. These effects cause three different types of distortion results. (1) The well-knownstatic shifts of sounding curves. (2) When the underlying regional setting is two-dimensional then the two regional impedances are mixed in an arbitrary coordinate system. Thus the level and shape of each sounding curve is distorted as are the phases. (3) At sufficiently high frequencies these effects generate anomalous magnetic fields that in turn alter the background phases.This tutorial first explores the usefulness of various MT tensor analysis techniques to overcome the problem of phase mixing and to recover regional information in the presence of local geological noise. Synthetic and experimental data are considered. A sequence ofa priori models of increasing complexity are described. The use of appropriate decompositions of the MT tensor each with an increasing number of parameters is emphasised. In a second part, phase mixing and static shifts are examined from a synoptic view. Some static shift removal techniques that can be used in conjunction with the decomposition are discussed. This paper is not a review but rather an investigation of a few methods that the authors have found useful with field data.  相似文献   

To analyze the Urban Water Pollution Discharge System using the tracking and tracing approach     

Zhenliang Liao  Guozheng Zhi  Yiwen Zhou  Zuxin Xu  Karsten Rink 《Environmental Earth Sciences》2016,75(14):1080

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Constraints on the magmatic evolution of the oceanic crust from plagiogranite intrusions in the Oman ophiolite     

Karsten M. Haase  Sarah Freund  Christoph Beier  Jürgen Koepke  Martin Erdmann  Folkmar Hauff 《Contributions to Mineralogy and Petrology》2016,171(5):46

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Petrogenesis of ultramafic and mafic xenoliths from Mesozoic basanites in southern Sweden: constraints from mineral chemistry     

Tatjana Rehfeldt  Karsten Obst  Leif Johansson 《International Journal of Earth Sciences》2007,96(3):433-450

Jurassic basanite necks occurring at the junction of two major fault zones in Scania contain ultramafic (peridotites, pyroxenites) and mafic xenoliths, which together indicate a diversity of upper mantle and lower crustal assemblages beneath this region. The peridotites can be subdivided into lherzolites, dunites and harzburgites. Most lherzolites are porphyroclastic, containing orthopyroxene and olivine porphyroclasts. They consist of Mg-rich silicates (Mg# = Mg/(Mg + Fe_tot) × 100; 88–94) and vermicular spinel. Calculated equilibration temperatures are lower in porphyroclastic lherzolites (975–1,007°C) than in equigranular lherzolite (1,079°C), indicating an origin from different parts of the upper mantle. According to the spinel composition the lherzolites represent residues of 8–13% fractional melting. They are similar in texture, mineralogy and major element composition to mantle xenoliths from Cenozoic Central European volcanic fields. Dunitic and harzburgitic peridotites are equigranular and only slightly deformed. Silicate minerals have lower to similar Mg# (83–92) as lherzolites and lack primary spinel. Resorbed patches in dunite and harzburgite xenoliths might be the remnants of metasomatic processes that changed the upper mantle composition. Pyroxenites are coarse, undeformed and have silicate minerals with partly lower Mg# than peridotites (70–91). Pyroxenitic oxides are pleonaste spinels. According to two-pyroxene thermometry pyroxenites show a large range of equilibration temperatures (919–1,280°C). In contrast, mafic xenoliths, which are mostly layered gabbronorites with pyroxene- and plagioclase-rich layers, have a narrow range of equilibration temperatures (828–890°C). These temperature ranges, together with geochemical evidence, indicate that pyroxenites and gabbroic xenoliths represent mafic intrusions within the Fennoscandian crust.  相似文献   

Collisional tectonics of the Baltic Shield in the northern Gulf of Bothnia from seismic data of the BABEL project     

Karsten Gohl  Laust B. Pedersen 《Geophysical Journal International》1995,120(1):209-226

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An intercomparison of regional climate model data for hydrological impact studies in Denmark     

Lieke van Roosmalen  Jens H. Christensen  Michael B. Butts  Karsten H. Jensen  Jens C. Refsgaard 《Journal of Hydrology》2010,380(3-4):406-419

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Model simulations of dense bottom currents in the Western Baltic Sea     

Hans Burchard  Frank Janssen  Karsten Bolding  Lars Umlauf  Hannes Rennau 《Continental Shelf Research》2009

Only recently, medium intensity inflow events into the Baltic Sea have gained more awareness because of their potential to ventilate intermediate layers in the Southern Baltic Sea basins. With the present high-resolution model study of the Western Baltic Sea a first attempt is made to obtain model based realistic estimates of turbulent mixing in this area where dense bottom currents resulting from medium intensity inflow events are weakened by turbulent entrainment. The numerical model simulation which is carried out using the General Estuarine Transport Model (GETM) during nine months in 2003 and 2004 is first validated by means of three automatic stations at the Drogden and Darss Sills and in the Arkona Sea. In order to obtain good agreement between observations and model results, the 0.5×0.5$0.5\times 0.5$ nautical mile bathymetry had to be adjusted in order to account for the fact that even at that scale many relevant topographic features are not resolved. Current velocity, salinity and turbulence observations during a medium intensity inflow event through the Øresund are then compared to the model results. Given the general problems of point to point comparisons between observations and model simulations, the agreement is fairly good with the characteristic features of the inflow event well represented by the model simulations. Two different bulk measures for mixing activity are then introduced, the vertically integrated decay of salinity variance, which is equal to the production of micro-scale salinity variance, and the vertically integrated turbulent salt flux, which is related to an increase of potential energy due to vertical mixing of stably stratified flow. Both measures give qualitatively similar results and identify the Drogden and Darss Sills as well as the Bornholm Channel as mixing hot spots. Further regions of strong mixing are the dense bottom current pathways from these sills into the Arkona Sea, areas around Kriegers Flak (a shoal in the western Arkona Sea) and north–west of the island of Rügen.  相似文献