Quantitative assessment of the area of shallow habitat for fish on the Swedish west coast     

Stal  Johan; Pihl  Leif 《ICES Journal of Marine Science》2007,64(3):446-452

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Food utilisation by coastal fish assemblages in rocky and soft bottoms on the Swedish west coast: Inference for identification of essential fish habitats   总被引：1，自引：1，他引：1  

Johan Stl  Leif Pihl  Hkan Wennhage 《Estuarine, Coastal and Shelf Science》2007,71(3-4):593-607

The concept of essential fish habitats (EFHs) is widely accepted for conservational and management purposes. EFHs are often considered as high quality habitats for fisheries species and subsequently of high values for society. In this study, fish and Substrate-Associated Prey (SAP) were sampled during the productive summer season 1998 (fish) and 2003 and 2004 (SAP) in shallow coastal rocky- and soft-bottom habitats on the Swedish west coast. The aim was to study the spatial and monthly variation of SAP as well as abundance and biomass of fish, and to examine if food items found in the diet of the fish assemblage were derived from SAP. We also examined if the diet of Ctenolabrus rupestris, a resident and abundant fish species in the shallow coastal habitats, and the diet of four seasonally abundant and commercially important fish species (Gadus morhua, Pleuronectes platessa, Salmo trutta and Scomber scombrus) were derived from SAP. There were significantly higher mean species number and abundance of the SAP assemblage on rocky compared to soft bottoms and the highest values were found on the rocky bottoms in August and in the shallowest (0–3 m) depth strata. There were no significant differences in number of fish species caught in the two habitats, although mean number of fish and mean biomass were significantly higher on rocky bottoms. Both habitats showed the same seasonal variation and the highest values of number of fish species, abundance and biomass were observed in June. On rocky bottoms, gastropods and amphipods were the most frequent food items in the diet of the entire fish assemblage and these items were also the most abundant SAP in this habitat. The dominant food items of the soft-bottom fish assemblage were decapods and fish, which were not common SAP. However, except for S. scombrus, the diet of the selected fish species showed a strong association to the SAP availability. Gadus morhua displayed the strongest association to SAP on rocky bottoms and P. platessa and C. rupestris to SAP on soft bottoms. Further, for C. rupestris, multivariate statistical analysis showed a significant association to the SAP assemblage on both rocky and soft bottoms. These results provide vital new information for the management and conservation of Essential Fish Habitats on the Swedish west coast.  相似文献   

The Diets in Four Pacific Tube Blennies (Acanthemblemaria: Chaenopsidae): Lack of Ecological Divergence in Syntopic Species     

David G.  Lindquist Kurt M.  Kotrschal 《Marine Ecology》1987,8(4):327-335

Abstract. The diets of three syntopic Gulf of California Acanthemblemaria (A. balanorum, A. crock-eri and A. macrospilus) and A. castroi from the Galapagos Island are nearly uniformly composed of harpacticoid copepods and other small benthic-vagile or planktonic crustaceans. On occasion, large prey items such as crabs or other small fishes are taken. HORN'S index of niche overlap indicates that the three syntopic Acanthemblemaria are not separated along the food resource utilization axis. Slight variations in diets among the syntopic species seem to be related to differences in degree of microhabitat specialization.  相似文献   

Inertia and a fifth dimension—special relativity from a new perspective     

C. Johan Masreliez 《Astrophysics and Space Science》2010,326(2):281-291

The phenomenon of inertia is modeled by a new process, which semi-discretely changes the metrical scale of spacetime. This process explains inertia as a curved spacetime phenomenon, since all accelerating trajectories take place on geodesics of general relativity. By this approach inertial reference frames are Minkowskian manifolds imbedded in a five-dimensional space. It would imply a revised interpretation of special relativity, which preserves a universal temporal reference. If acceleration curves spacetime, it would also imply the existence of an energy-momentum tensor with net energy, which under certain conditions could become negative.  相似文献   

European temperature records of the past five centuries based on documentary/instrumental information compared to climate simulations     

Eduardo Zorita  Anders Moberg  Lotta Leijonhufvud  Rob Wilson  Rudolf Brázdil  Petr Dobrovolný  Jürg Luterbacher  Reinhard Böhm  Christian Pfister  Dirk Riemann  Rüdiger Glaser  Johan Söderberg  Fidel González-Rouco 《Climatic change》2010,101(1-2):143-168

Two European temperature reconstructions for the past half-millennium, January-to-April air temperature for Stockholm (Sweden) and seasonal temperature for a Central European region, both derived from the analysis of documentary sources and long instrumental records, are compared with the output of climate simulations with the model ECHO-G. The analysis is complemented by comparisons with the long (early)-instrumental record of Central England Temperature (CET). Both approaches to study past climates (simulations and reconstructions) are burdened with uncertainties. The main objective of this comparative analysis is to identify robust features and weaknesses in each method which may help to improve models and reconstruction methods. The results indicate a general agreement between simulations obtained with temporally changing external forcings and the reconstructed Stockholm and CET records for the multi-centennial temperature trend over the recent centuries, which is not reproduced in a control simulation. This trend is likely due to the long-term change in external forcing. Additionally, the Stockholm reconstruction and the CET record also show a clear multi-decadal warm episode peaking around AD 1730, which is absent in the simulations. Neither the reconstruction uncertainties nor the model internal climate variability can easily explain this difference. Regarding the interannual variability, the Stockholm series displays, in some periods, higher amplitudes than the simulations but these differences are within the statistical uncertainty and further decrease if output from a regional model driven by the global model is used. The long-term trend of the CET series agrees less well with the simulations. The reconstructed temperature displays, for all seasons, a smaller difference between the present climate and past centuries than is seen in the simulations. Possible reasons for these differences may be related to a limitation of the traditional ‘indexing’ technique for converting documentary evidence to temperature values to capture long-term climate changes, because the documents often reflect temperatures relative to the contemporary authors’ own perception of what constituted ‘normal’ conditions. By contrast, the amplitude of the simulated and reconstructed inter-annual variability agrees rather well.  相似文献   

Regional Flow in the Baltic Shield During Holocene Coastal Regression   总被引：2，自引：0，他引：2  

Clifford I. Voss  Johan Andersson 《Ground water》1993,31(6):989-1006

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Floodfan sedimentation and gravitational anomalies in the Salar de Punta Negra,Northern Chile     

Ronald A. van Overmeeren  Johan H. Staal 《International Journal of Earth Sciences》1976,65(1):195-211

The Upper Tertiary inter-andean tectonic trough of the Salar de Punta Negra is being filled mainly through sporadic flash-floods by denudation products from the East (Andes). Borehole records up to 430 m deep suggest depositional conditions similar to the actual ones.Block tectonic movements with N-S and NNE-SSW directions from Upper Tertiary through Pleistocene affected the normal morphology of the fans.Gravity survey has corfirmed a tectonic origin of the basin. East of the Salar, a buried graben with an alluvial fill of 550–750 m thickness was found, which may contain a groundwater reservoir.

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Zusammenfassung Der jungtertiäre intra-andine Graben des Salars Punta Negra wurde durch sporadische Flutfächer vorwiegend aus dem Osten (Hochkordillere) gefüllt. Bohrungen bis 430 m Tiefe zeigen ähnliche Fanglomerate, wie sie heute entstehen.Verwerfungen mit N-S- und NNE-SSW-Richtungen zwischen Jungtertiär und Pleistozän beeinflussen die Morphologie der Schuttfächer.Gravimetrische Messungen ergaben, daß die Depression tektonisch angelegt ist. Östlich des heutigen Salars liegt ein verschütteter Graben mit einer alluvialen Füllung von mindestens 550–750 m Dicke. Hier könnte ein Grundwasser-Reservoir liegen.

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Resumen El graben intra-andino del Salar de Punta Negra de edad Terciario Superior ha sido esporádicamente rellenado por conos aluviales. Estos vienen principalmente del este desde la Alta Cordillera. Perforaciones que han llegado hasta 430 m de profundidad muestran fanglomerados semejantes a los que se forman actualmente.Una tectónica de bloques de dirección N-S y NNE-SSW entre el Terciario Superior y el Pleistoceno afectan la morfología de los conos aluviales.Mediciones gravimétricas permiten concluir que la depresión tiene origen tectónico. Al oriente del Salar aparece un graben relleno de materiales aluviales con una potencia entre 550–750 m. Este graben puede contener acuíferos profundos de utilidad local.

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Résumé Le graben intra-andin Cénozoïque Supérieur du Salar de Punta Negra se comble par des courants torrentueux sporadiques de produits de dénudation venant surtout de l'Est (Haute Cordillère). Des forages atteignant 430 m de profondeur suggèrent des conditions de dépôt similaires aux actuelles.Des failles N-S et NNE-SSW actives depuis le Cénozoïque Supérieur jusqu'au Pléistocène ont affecté la morphologie des cônes de déjection.Les mesures gravimétriques confirment l'origine tectonique du bassin de Punta Negra. A l'Est du Salar est situé un graben totalement enfoui de dépôts alluviaux d'une puissance d'environ 550–750 m, où des nappes aquifères exploitables sont susceptibles d'exister à grande profondeur.

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The significance of mafic nodules in the ultra-potassic rocks from central Italy - discussion     

Johan C. Varekamp 《Journal of Volcanology and Geothermal Research》1983,16(1-2)

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La parapierrotite,un nouveau minéral thallifère d'Allchar (Yougoslavie)     

Dr. Z. Johan  Dr. P. Picot  Dr. J. Hak  Dr. M. Kvaček 《Mineralogy and Petrology》1975,22(3-4):200-210

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Paleomagnetism in deep-sea core A179-15     

Nils-Axel Mörner  Johan Lanser 《Earth and Planetary Science Letters》1975,26(1):121-124

Core A179-15 from the southern North Atlantic exhibits one of the best paleoclimatic records for the last 25,000 years. This is because it is a high-sedimentation rate core and because it has been analysed at 1 cm intervals by Ericson and Wollin. The core has been used by Mörner for global climatic correlations. The magnetic measurements show a fairly drastic declination excursion at 12,350 B.P., i.e. exactly at the same age as the end of the Gothenburg Magnetic “Flip”. Therefore, the declination excursion in core A179-15 probably represents the end of the Gothenburg Magnetic “Flip” and Excursion. The excursion and a lithologic boundary verify the chronology earlier applied by Mörner.  相似文献