Ecotopic and ontogenetic trophic variation in mojarras (Pisces: Gerreidae)     

Barbara A. Kerschner  Mark S. Peterson  R. Grant Gilmore 《Estuaries and Coasts》1985,8(3):311-322

Seven species of mojarras (Gerreidae) were collected from three stations in the Indian River lagoon near the Sebastian Inlet, Florida over an eighteen month period to study spatial and temporal variations in occurrence and feeding habits. Two major habitats common to this area were represented in the study; a sandy beach and a seagrass flat. Of the 2,899 gerreids collected,Eucinostomus gula represented 67% and was found primarily in theHalodule seagrass site. The next most abundant species,E. argenteus (11%),E. jonesi andE. lefroyi (each 10%), were found most frequently at the inlet site.Diapterus auratus, E. melanopterus, andGerres cinereus were captured infrequently and were considered incidental. Prey items found included amphipods, bivalves, copepods, fish eggs, foraminifera, isopods, nematodes, ostracods, polychaetes and crustacean parts. Significant amounts of sand and unidentifiable amorphous debris were also included in the gut content analysis. Little interspecific variation in diet was found among the four major species examined. The general shift seen from a diet composed primarily of copepods and other crustaceans to one of polychaetes suggests an intraspecific ontogenetic progression. Spatial variations in diet composition were also indicated between the two major habitats. Feeding analyses showed gerreids to be diurnal feeders with the greatest consumption (total gut content weight) occurring at dusk.  相似文献   

THE OCCURRENCE AND DEVELOPMENT OF GUEST SINK, HERNANDO COUNTY, FLORIDA     

Barbara A. Boatwright  David W. Allman 《Ground water》1975,13(4):372-375

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Surface circulation of the Indian Ocean during the last glacial maximum, approximately 18,000 yr B.P.     

Warren L. Prell  William H. Hutson  Douglas F. Williams  Allan W. H. B  Kurt Geitzenauer  Barbara Molfino 《Quaternary Research》1980,14(3):309-336

A seasonal reconstruction of the Indian Ocean during the last glacial maximum (18,000 yr B.P.) reveals that its surface circulation and sea surface temperature patterns were significantly different from the modern Indian Ocean. This reconstruction is based on the planktonic foraminiferal biogeography and estimated sea surface temperatures in 42 Indian Ocean samples. Compared to modern conditions, the polar front was 5° to 10° latitude further north during the last glacial maximum; the Subtropical Convergence was 2° to 5° latitude further north. The West Australian Current was more intense as part of the West Wind Drift was deflected northward along the coast of Australia. The Agulhas Current was cooler and weaker during the summer and more saline and subtropical during the winter. In general, the low latitudes underwent little temperature change. The western Arabian Sea was warmer which implies less upwelling and a weaker Southwest Monsoon. On the average, the Indian Ocean was 1.9°C cooler in February and 1.7°C cooler in August during the last glacial maximum.  相似文献   

On the resolution of density anomalies in the Earth's mantle using spectral fitting of normal-mode data     

Chaincy Kuo  Barbara Romanowicz 《Geophysical Journal International》2002,150(1):162-179

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Site response zones and short-period earthquake ground motion projections for the Las Vegas Basin     

Barbara Luke  Ying Liu 《Journal of Earth System Science》2008,117(2):757-772

A deterministic seismic hazard analysis was conducted to address the effect of local soil conditions on earthquake-induced strong ground motion in the Las Vegas Basin, Nevada (US). Using a large geological and geotechnical database, two response units were defined: a fine-grained unit, predominantly clay; and a coarse-grained unit, predominantly gravel. A moderate number of high-quality shallow shear wave velocity measurements were collected from which characteristic shear wave velocity profiles were developed for each response unit. An equivalent-linear one-dimensional site response model was used. The model was calibrated using a basin-wide, small-strain ground motion database. Calibration tests showed that ground motion projections become increasingly conservative with increasing ground-motion amplitude. Projections were overconservative for the coarse-grained response unit, likely due to the sparseness of the velocity database. For the earthquake response analyses, historical ground motions were used to model characteristic ‘bedrock’ motion for earthquakes on 10 faults judged to be critical. Response spectral envelopes were generated for each unit through Monte-Carlo simulations. For the fine-grained response unit, 95th percentile peak ground acceleration, peak spectral acceleration and predominant period were 310 cm/s², 1100 cm/s², and 0.29 s, respectively. With respect to codified design spectra, projections are lower at short periods and higher at long periods. Projections of peak spectral accelerations for the coarse-grained response unit, were more than double that of codified spectra; however, they are believed to be overconservative. Near-fault effects and basin-edge effects, though potentially important, were not considered in these analyses.  相似文献   

The accumulation of Cu, Zn, Cd, and Pb in the aquatic biomass of sulphide tailing ponds     

Elena I. Khozhina  Barbara L. Sherriff 《Geochemistry International》2008,46(9):897-911

Flooding mine tailings to limit the oxidation of sulfides provides a habitat for aquatic organisms, such as plants, plankton, insects, and fish, which can uptake metals and, thus, threats for local ecosystems and influence the cycling of elements in biogeocenosis. An aquatic ecosystem developed naturally in sulphide tailing ponds containing cyanidation wastes of the Salair ore-refining plant (SORP), Russia, was studied. The objectives of this research were to: (i) reveal the level of contamination of living organisms in the tailing ponds compared to a natural control site and (ii) calculate the weight of metals in aquatic biomass to estimate the amount of metals transferring from the tailing ponds into the biogechemical cycle. The concentration of Cu, Zn, Cd, and Pb in the sediments of the tailing ponds is significantly higher than from the control site. Concentrations of Cu, Zn, Cd, and Pb in plant shoots were significantly higher than in the control and accumulated mainly in cell envelopes and membranes. The concentration of Pb in fish liver and eggs were 41 and 7.5 times higher, respectively, than maximum allowable concentrations. The biomass distribution between producers and consumers of the tailing pond ecosystem is similar to those of natural pond ecosystems. However, the weights of Cu, Zn, Cd, and Pb in all trophic levels per hectare of the tailing pond are orders of magnitude higher than those for Lake Baikal. The largest portion of metal circulates within the ecosystem of the Dyukov Ravine Pond with a maximum of 5 to 13% of this amount transferred into the surrounding environment through the food chains.  相似文献   

Direct versus indirect determination of suspended sediment associated metals in a mining-influenced watershed     

Barbara A. Butler  James F. Ranville  Philippe E. Ross 《Applied Geochemistry》2008

The differentiation between the concentration of metals associated with suspended sediments and those in the dissolved phase is often of importance in aquatic ecosystems, for such reasons as toxicity evaluation, total maximum daily load calculations, and a better understanding of metal transport. Often, published water quality data include only concentrations of total and dissolved metals, with particulate concentrations assumed equal to the difference between the two. The validity of this assumption for mining-influenced waters is addressed in this paper by comparing data determined from the subtraction of total (acid-soluble) and dissolved (operationally defined as less than 0.45-μm) metal concentrations (difference method) with data obtained from acid-digestion of the particles retained on the filters used for filtering the dissolved fraction (digestion method). Greater than fifty water samples containing suspended sediment were collected from each of three sites in the Clear Creek Watershed in Colorado during a two and one-half year study on the fate and transport of metals in the watershed. Volumes of water filtered ranged from 50 to 250 ml, representative of typical volumes used for the determination of dissolved metal concentrations. The particulate-associated concentrations of Al, Cu, Fe, Mn, and Zn determined from the difference method compared well with the concentrations determined by the digestion method. Statistical analyses indicated that there is not a statistically significant difference between the two methods at the 95% confidence level, with p-values of 0.65, 0.88, 0.39, 0.67, and 0.75, for Al, Cu, Fe, Mn, and Zn, respectively, over the three sites.  相似文献   

Riparian vegetation as indicator of channel adjustments and environmental conditions: the case of the Panaro River (Northern Italy)     

Bruna Gumiero  Massimo Rinaldi  Barbara Belletti  Daniele Lenzi  Giovanna Puppi 《Aquatic Sciences - Research Across Boundaries》2015,77(4):563-582

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Automated assessment of macroseismic intensity from written sources using the fuzzy sets     

Gianfranco Vannucci  Daniele Tripone  Paolo Gasperini  Graziano Ferrari  Barbara Lolli 《Bulletin of Earthquake Engineering》2015,13(10):2769-2803

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X-ray studies of flaring plasma     

B. Sylwester  J. Sylwester  K. J. H. Phillips 《Journal of Astrophysics and Astronomy》2008,29(1-2):147-150

We present some methods of X-ray data analysis employed in our laboratory for deducing the physical parameters of flaring plasma. For example, we have used a flare well observed with Polish instrument RESIK aboard Russian CORONAS-F satellite. Based on a careful instrument calibration, the absolute fluxes in a number of individual spectral lines have been obtained. The analysis of these lines allows us to follow the evolution of important thermodynamic parameters characterizing the emitting plasma throughout this flare evolution.  相似文献