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1.
A range of biological traits of nematode species were combined to identify patterns in the functional composition of their assemblages collected at 19 soft-bottom stations in the southwestern North Sea with the primary aim to determine which environmental variables control communities. We used 19 categories of five biological traits thought or known to represent an important ecological function. These were related to buccal morphology, tail shape, body size, body shape and life history strategy. Data on trait membership was provided by biological information on species and genera. A total of 79 different trait combinations were recorded. Results from correlation analyses revealed several significant relationships between traits. Some trait combinations were shared by different species and genera, and the ratio of realised versus total number of possible trait combinations of < 1 suggested that some trait combinations were not represented by the nematode fauna from this region. The functional composition of nematodes was strongly linked to median particle diameter and silt content of the sediment and water depth. The approach adopted and our attempts at defining and analysing functional attributes of nematode communities raised a number of conceptual and methodological issues which are discussed. 相似文献
2.
东海盆地丽水凹陷古新统锆石示踪作用分析 总被引：4，自引：0，他引：4
锆石具有较强的稳定性，是地质研究中一种强有力的工具。通过对其形态学研究，再结合其地球化学特征，可讨论其母岩的成因；同时，结合颗粒锆石的微区定年，可以讨论重要的地质事件成因和演化，如锆石的成因和微区离子探针技术在研究造山带构造年代学中发挥着重要作用。利用激光探针等离子体质谱(LAM-ICPMS)技术对丽水凹陷古新统沉积岩中锆石进行微区定年和微量元素测定，并对稀土元素配分模式和微量元素特征进行分析，结果表明，对于复杂来源的锆石，利用其地球化学特征进行区分效果不理想，锆石地球化学特征并不是有利的沉积和锆石来源显示。 相似文献
3.
Understanding long-term trends in species abundance and distribution represents an important challenge for future research in the deep sea, particularly as management of human impacts becomes a more important concern. However, until natural higher frequency variability is better understood, it will be difficult to interpret any long-term trends that may be apparent in data sets. We present here the results of the first year of observations at the NEPTUNE Canada cabled observatory site in Barkley Canyon, off the coast of Vancouver Island, in the northeast Pacific Ocean. Presence/absence and abundance data for 28 faunal groups were extracted from daily video records from an observatory camera. Concurrent CTD and current meter data were collected from co-located instruments. Water mass properties, currents and faunal community composition exhibited notable seasonal trends. Distinct seasonal faunal groupings were observed, together with summer and winter trends in temperature, salinity and current patterns. Variations in abundance of decapod crustaceans and fishes were responsible for most differences between faunal groups. We suggest that faunal composition may have been responding to seasonal variations in food availability, together with direct and indirect physical influences on predator and prey abundance. 相似文献
4.
Macrofaunal nematodes of the deep Whittard Canyon (NE Atlantic): assemblage characteristics and comparison with polychaetes 
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下载免费PDF全文 Laetitia M. Gunton Brian J. Bett Andrew J. Gooday Adrian G. Glover Ann Vanreusel 《Marine Ecology》2017,38(2)
Large nematodes form an important component of deep‐sea macrofaunal assemblages, but are often considered to be part of the meiobenthos and are rarely studied. We analysed the standing stocks, diversity, and functional group and genus‐level composition of macrofaunal nematodes at lower bathyal depths (3,500 m water depth) in the Whittard Canyon system (NE Atlantic) and on the adjacent continental slope. Five replicate sample sets were obtained using a Megacorer, at four locations (three canyon branches, one slope). Sediment samples were processed on a 500‐μm mesh to provide both nematode and polychaete data from the same samples. The dominant nematode genera included Paramesacanthion, Metacylicolaimus, Cylicolaimus and Phanodermopsis. Nematode standing stocks (density and biomass) increased significantly from slope to canyon locations. Similarly, nematode dominance increased substantially (and diversity decreased) from slope to canyon locations. Nematode feeding groups and tail shape groups also appeared to exhibit common trends across study locations. Nematode genus‐level faunal composition varied significantly between slope and canyon locations. We describe and discuss the broadly similar trends detected in the matching polychaete data, noting some differences in the polychaete density and diversity responses. We suggest that the similar trends in macrofaunal nematode and polychaete ecology across our four study locations reflect responses to both changing sedimentology and food availability. 相似文献
5.
Chiranjeeb Sarkar Sridhar D. Iyer Sugata Hazra 《Marine Georesources & Geotechnology》2013,31(4):259-289
More than 200 samples of manganese nodules from the Central Indian Ocean Basin (CIOB) were studied for their different parameters. The study included various aspects such as morphology, texture, mineralogy, and composition of the nodules. The nuclei of the nodules were also examined along with the oxide layers. We attempt to correlate the nucleus (their type and abundance) with the nodule parameters such as their external morphology, chemical composition, and suitable location of formation, amongst others. We found various nucleating materials and these include rock fragments (fresh and altered), clay, pumice and sharks' teeth. In a majority of the cases, rock fragments are dominant in the core of the nodules and these conform to that of the seafloor basalts. The shape of the nuclei influences that of the nodules, especially during their initial period of growth. Irrespective of the kind of nuclei, todorokite is the main mineral of the nodules. The nodules of the CIOB were formed mostly due to hydrogenous accretion of ferromanganese oxides while diagenetic contribution of metals is less common. 相似文献
6.
Soundings on nautical charts provide information about the shape of the ocean bottom between chart depth curves. A single chart may have thousands of soundings posted on it. This article describes a system for automatic cartographic sounding selection. In this system, a new algorithm for automated selecting soundings is developed. The algorithm is employed in such a way that it can guarantee (a) fast and accurate selecting sounding, (b) processing the circular depth curves, (c) solving the overplotting problems between depth curves and soundings, and (d) keeping selected soundings “prettier.” The system was intensively tested using real data sets, and its superiority has been revealed by the testing results. 相似文献
7.
Soundings on nautical charts provide information about the shape of the ocean bottom between chart depth curves. A single chart may have thousands of soundings posted on it. This article describes a system for automatic cartographic sounding selection. In this system, a new algorithm for automated selecting soundings is developed. The algorithm is employed in such a way that it can guarantee (a) fast and accurate selecting sounding, (b) processing the circular depth curves, (c) solving the overplotting problems between depth curves and soundings, and (d) keeping selected soundings “prettier.” The system was intensively tested using real data sets, and its superiority has been revealed by the testing results. 相似文献
8.
Takuji Waseda Leland Jameson Humio Mitsudera Max Yaremchuk 《Journal of Oceanography》2003,59(2):187-200
Wavelet Analysis provides a new orthogonal basis set which is localized in both physical space and Fourier transform space.
Empirical Orthogonal Functions (EOFs), on the other hand, provide a global representation of data sets. Here we investigate
the various ways in which one can combine these basis sets for optimal representation of data. EOFs represent the global large
scale information and wavelet analysis are used to supplement this large scale information with local fine scale information.
Here we begin to explore the application of these two basis sets for outputs from an Ocean General Circulation Model and we
explore various applications, including data assimilation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Xiaofeng Yang Aiguo Nie Derek Elsworth Jiaheng Zhou 《Marine Georesources & Geotechnology》2020,38(5):511-517
AbstractRock drilling is a significant activity widely used in the exploration of marine mineral resources and offshore civil engineering such as marine mining, petroleum and deep-water drilling. The characteristics of size and shape of particles produced during rock drilling influence drilling efficiency and energy consumption. We report a series of drilling experiments on sandstone, limestone and shale to systematically examine particle size distribution and shape and correlate these with original rock structure and composition. Correlations are established via metrics of particle size distribution, average circularity and specific surface area. Impact breakage and contact abrasion of individual particles during rock drilling are the main mechanisms controlling particle size and shape. Impact breakage is controlled by the structural distribution of mineral phases, while contact abrasion is principally related to the hardness of mineral phases. The particle size distribution is affected by the structural distribution of mineral phases. The average circularity of the drilling particles is mainly controlled by the hardness of mineral phases. The specific surface area of rock drilling particles is determined by both structural distribution and hardness of mineral phases – with homogeneous structure and low average hardness of the phases reducing the resulting specific surface area of the drilling products. 相似文献
10.
We investigated seasonal changes in carbon demand and flux by mesozooplankton communities at subtropical (S1) and subarctic sites (K2) in the western North Pacific Ocean to compare the impact of mesozooplankton communities on the carbon budget in surface and mesopelagic layers. Fecal pellet fluxes were one order higher at K2 than at S1, and seemed to be enhanced by copepod and euphausiid egestion under high chlorophyll a concentrations. The decrease in pellet volume and the lack of any substantial change in shape composition during sink suggest a decline in fecal pellet flux due to coprorhexy and coprophagy. While respiratory and excretory carbon by diel migrants at depth (i.e., active carbon flux) was similar between the two sites, the actively transported carbon exceeded sinking fecal pellets at S1. Mesozooplankton carbon demand in surface and mesopelagic layers was higher at K2 than S1, and an excess of demand to primary production and sinking POC flux was found during some seasons at K2. We propose that this demand was met by supplementary carbon sources such as feeding on protozoans and fecal pellets at the surface and carnivory of migrants at mesopelagic depths. 相似文献
11.
YE Huping ZHANG Bing LIAO Xiaohan LI Tongji SHEN Qian ZHANG Fangfang ZHU Jianhua LI Junsheng 《海洋湖沼学报（英文）》2019,(5):1542-1554
The absorption spectrum of phytoplankton is an important bio-optical parameter for ocean color hyperspectral remote sensing;its magnitude and shape can be aff ected considerably by pigment composition and concentration. We conducted Gaussian decomposition to the absorption spectra of phytoplankton pigment and studied the spectral components of the phytoplankton, in which the package effect was investigated using pigment concentration data and phytoplankton absorption spectra. The decomposition results were compared with the corresponding concentrations of the five main pigment groups (chlorophylls a , b , and c , photo-synthetic carotenoids (PSC), and photo-protective carotenoids (PPC)). The results indicate that the majority of residual errors in the Gaussian decomposition are <0.001 m^-1 , and R 2 of the power regression between characteristic bands and HPLC pigment concentrations (except for chlorophyll b) was 0.65 or greater for surface water samples at autumn cruise. In addition, we determined a strong predictive capability for chlorophylls a , c , PPC, and PSC. We also tested the estimation of pigment concentrations from the empirical specific absorption coeffi cient of pigment composition. The empirical decomposition showed that the Ficek model was the closest to the original spectra with the smallest residual errors.The pigment decomposition results and HPLC measurements of pigment concentration are in a high consistency as the scatter plots are distributed largely near the 1:1 line in spite of prominent seasonal variations. The Wozniak model showed a better fit than the Ficek model for Ch1 a , and the median relative error was small. The pigment component information estimated from the phytoplankton absorption spectra can help better remote sensing of hyperspectral ocean color that related to the changes in phytoplankton communities and varieties. 相似文献
12.
Despite the availability of 3D CAD systems, the designers in shipyards still use 2D CAD systems because of the need to produce drawings rapidly and a shortage of labor. The shipyard spends much time and labor analyzing the design information contained in 2D drawings and creating 3D model for the downstream processes. The design information is represented by symbols that are well known among designers in shipyard. Symbols are expressed by meaningless geometric shapes. These shapes are recognized to have meanings by analysis of experienced and knowledgeable designers.We propose a method for automatic recognition of 2D symbols and the extraction of design information from the midship drawings. The shape and rationale of 2D symbols used in ship design have been analyzed, and symbols have been classified according to the analysis. Based on the classified symbols, the developed system recognizes the symbols expressed in 2D drawings. The extracted design information is assorted by design rationales. The meaningless geometric shape is translated into the design information including designer's intents. The extracted design data can be applied to the design process in shipyards, and the 3D ship model can be automatically created. 相似文献
13.
Analytical results of sound velocity and spectrum for seafloor sediment ore obtained by VWA (velocity-wave-amplitude) discrimination technique. Based on velocity-wave-amplitude, an understanding is gained of the physical condition and structural characteristics of seafloor sediment, which is combined with other geological information of the sedimentary layer to synthetically discriminate the properties of seafloor sediment. Experimental results show that, by using the relationship between sound velocity, wave form envelope, amplitude shape and size, and such parameters as sedimentary structure, microstructure, bedding, grain composition, mineral composition, and physical-mechanics, etc., the basic properties of the shallow surface seafloor sediment in the experimental sea area can be discriminated and the burial depth of traces of ancient marine transgression and regression events in the borehole cores of seafloor sediment can be divided, thus making an attempt of and contribution to the practice of acoustically remote-sensing and telemetering seafloor sediment. 相似文献
14.
Analytical results of sound velocity and spectrum for seafloor sediment ore obtained by VWA (velocity-wave-amplitude) discrimination technique. Based on velocity-wave-amplitude, an understanding is gained of the physical condition and structural characteristics of seafloor sediment, which is combined with other geological information of the sedimentary layer to synthetically discriminate the properties of seafloor sediment. Experimental results show that, by using the relationship between sound velocity, wave form envelope, amplitude shape and size, and such parameters as sedimentary structure, microstructure, bedding, grain composition, mineral composition, and physical-mechanics, etc., the basic properties of the shallow surface seafloor sediment in the experimental sea area can be discriminated and the burial depth of traces of ancient marine transgression and regression events in the borehole cores of seafloor sediment can be divided, thus making an attempt of and contribution to the practice of acoustically remote-sensing and telemetering seafloor sediment. 相似文献
15.
Towed array beamforming algorithms require accurate array shape information in order to perform properly. Very often, these algorithms assume the array is linear. Unfortunately, the mechanical forces on the array due to ship motion and sea dynamics can change the shape of the array, which degrades the performance of the beamforming algorithm. A data-driven approach to estimating the relative shape of a nominally linear array is presented. The algorithm is robust in that it optimally combines information contained in a wide band of frequencies and source bearings. At the heart of the algorithm is a maximum-likelihood (ML) estimation scheme. The Cramer-Rao lower bound is derived and compared to the performance of the ML estimator. The utility of the algorithm is verified using both simulated and actual towed array data experiments 相似文献
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17.
Ronald E. Thresher Colin M. MacRae Nick C. Wilson Stewart Fallon 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(3):442-449
We test two hypotheses, that annual environmental cycles produce periodic variability in the skeletal composition of deep-water gorgonians, and that these cycles can be counted to determine the coral's age. Annual periodicity of deposition was tested by comparing the internode composition of bamboo corals live-collected 10 years apart in the Southern Ocean. The validity of the comparison was substantiated by growth rates for the 10-year interval (77–121 μm/yr) that were confirmed by radiocarbon analysis. Variability in Mg/Ca and possibly S/Ca, but not Sr/Ca or P/Ca, was consistent with annual cycles of deposition. However, spectral analysis of Mg/Ca data for a larger coral showed little or no spectral peak associated with an annual cycle of deposition (though there were peaks at periods of 4–5 and 11–15 years). The absence of an annual peak is likely to reflect growth rates that vary over time, coral cross-sections that change shape over time, and interannual differences in the seasonal range of environmental variability. The resulting subjectivity in what defines an annulus, along with evidence that the nature and extent of annual periodicity differs among sites, means that the technique is likely to be inherently imprecise and to require independent validation for each site and taxon before it can be applied. 相似文献
18.
Using a proper approximation scheme to the centrifugal term, we study any l-wave continuum states of the Schrõdinger equation for the modified Morse potential. The normalised analytical radial wave functions are presented, and a corresponding calculation formula of phase shifts is derived. It is shown that the energy levels of the continuum states reduce to those of the bound states at the poles of the scattering amplitude. Some numerical results are calculated to show the accuracy of our results. 相似文献
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Neutral aldoses as source indicators for marine snow 总被引：2，自引：0，他引：2
Annelie Skoog Alice Alldredge Uta Passow John Dunne James Murray 《Marine Chemistry》2008,108(3-4):195-206
The chemical characteristics of aggregating material in the marine environment are largely unknown. We investigated neutral aldose (NA) abundance and composition in aggregation of marine snow and other organic matter (OM) size fractions in the field. Four sample sets were fractionated using membrane filtration and ultrafiltration into the following size fractions: particulate material, high-molecular-weight (HMW) material, and low-molecular-weight (LMW) material. We also collected three sample sets of marine-snow aggregates. Each sample set contained small, medium, and large aggregate size fractions and each size fraction consisted of 25–50 aggregates. For 7 marine-snow samples and for each water-sample size fraction, we determined monomeric and polymeric NA concentration, NA yield (amount of NA-C normalized to organic carbon), and composition; total organic carbon (TOC) concentration; transparent exopolymer particles (TEP) concentration, and TEP propensity (TEP concentration after inducing TEP formation in filtered samples). This is the first study to include compound-specific NA determinations on these four marine OM size fractions.The mass balances of organic carbon and NA indicated that there were no serious contamination or loss problems. Concentrations, yields, and NA mol fractions in water samples were similar to results from other studies. Glucose and galactose had the highest relative abundance in all size fractions. The NA yield increased with increasing molecular weight or particle size for all fractions except marine snow. The NA yield increased in the order: LMW< marine snow< HMW< particles. Marine snow had a higher average NA yield than the LMW fraction, but lower than particle and HMW-fractions. This indicates that OM in marine snow could have been diagenetically derived from particulate and HMW-fractions, that is, marine snow may include material from the particulate and the colloidal phase.TEP concentration or TEP propensity was positively correlated with concentrations of all individual NAs as well as the sum NA concentrations, indicating that TEP contains neutral sugars in addition to the acidic polysaccharides stained in the determination of TEP concentrations.Despite the relatively low NA yield in marine snow, marine snow was enriched in NA when compared with seawater, with enrichment factors of 34–225 (average 125). By combining data from this study with data from other studies, we estimate that < 10% of carbohydrates in marine snow comprise NAs.There was no clear correlation between marine-snow aggregate size and NA yield, that is, there appears to be no general age difference between small and large marine-snow aggregates. NA composition was similar among different marine-snow size fracions collected during the same day, indicating that aggregation/disaggregation reactions resulted in homogenizing NA composition in marine-snow aggregates of all sizes. The NA composition of marine snow was different from that of other OM size fractions, indicating either that bacterial degradation has modified the composition of marine snow to a larger extent than other OM size fractions or that marine snow is formed through the aggregation of selected subcomponents of OM. 相似文献