Understanding mackerel migration off Scotland: Tracking with echosounders and commercial data, and including environmental correlates and behaviour     

Walsh  Martin; Reid  David G.; Turrell  William R. 《ICES Journal of Marine Science》1995,52(6):925-939

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Relative molar mass distributions of chromophoric colloidal organic matter in coastal seawater determined by Flow Field-Flow Fractionation with UV absorbance and fluorescence detection     

Martin Hassellv 《Marine Chemistry》2005,94(1-4):111

A new method for the characterization of chromophoric colloidal organic matter in seawater has been applied to samples from the Baltic Sea, Kattegatt and Skagerrak seas. Size fractionation of the sample by Flow Field-Flow Fractionation and measurement of the fluorescent and UV absorbing properties of the individual size fractions result in a relative molar mass distribution (RMM) of the optical properties. The RMM distributions have been used to estimate number and weight average relative molar masses, and polydispersity indices. At least two sources of coloured organic matter were identified from the ratio of fluorescence to UV: the Baltic surface water and the Skagerrak deep water. The dominating processes were mixing and dilution, but processes such as photo bleaching of fluorescence are also believed to be important. The RMM distribution derived from UV detection (1150–1300 Dalton) increased with increasing salinity while that derived for fluorescence (1500–1250 Dalton) decreased with increasing salinity. The specific UV absorbance taken as a proxy of the aromaticity of the chromophoric organic material showed decreasing trend with both increasing salinity and increasing UV derived weight average relative molar mass. Increasing polydispersity of the colloidal material was also observed as a function of salinity.  相似文献   

Validating management simulation models and implications for communicating results to stakeholders     

Pastoors  Martin A.; Poos  Jan Jaap; Kraak  Sarah B. M.; Machiels  Marcel A. M. 《ICES Journal of Marine Science》2007,64(4):818-824

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Selenium distribution in the Rhône delta and the Gulf of Lions     

Dao Ming Guan  Jean-Marie Martin 《Marine Chemistry》1991,36(1-4)

Total dissolved selenium and selenium species have been measured in the Rhône river delta and the Gulf of Lions within the framework of the EROS-2000 project. The Rhône river concentration of total selenium averages 2.30 nM with important variations related to river discharge. During estuar-ine mixing, the concentrations of total dissolved selenium, selenite and selenate (calculated as the difference between total dissolved and selenite) decrease linearly with increasing salinity, without significant interconversion between selenium species. In the open Mediterranean waters of the Gulf of Lions the total dissolved selenium increases from 0.5 nM in the surface waters to 0.9 nM in the deep waters. Organic selenium has been observed in Mediterranean deep water, an observation which is different from those from the Atlantic and the Pacific Oceans. The distributions of total inorganic selenium (Σ5e), selenite and selenate are strongly related to phosphate and silicate concentrations as observed previously for the major oceans.  相似文献   

Particle-bound phosphorus along an urbanized coastal plain estuary   总被引：1，自引：0，他引：1  

Martin E. Lebo 《Marine Chemistry》1991,34(3-4)

The distribution of particle-bound phosphorus in the suspended sediment of the Delaware Estuary was examined with a sequential chemical leaching technique. The phosphorus content of particles was highest in the tidal river (140–250 μmol g⁻¹) near major anthropogenic inputs. Despite this enrichment of river particles with phosphorus, suspended particles within the salinity gradient had a phosphorus content more similar to the world's average. Sequential chemical leaches revealed that particulate phosphorus was associated with organic matter, aluminum oxides, iron oxides, and apatite in all areas of the estuary. However, ‘excess’ particle-bound phosphorus in the tidal river was associated mainly with iron oxides (27%), aluminum oxides (23%), and organic matter (50%). Within the salinity gradient, particulate phosphorus associated with iron oxides, aluminum oxides, and apatite all decreased with increasing salinity. Estuarine mixing was simulated to determine whether the observed decreases in particle-bound phosphorus pools in field samples were due to release into solution. During simulated mixing, particulate phosphorus associated with iron and aluminum oxides decreased, but no change was observed in apatite-bound phosphorus. The results of the mixing study combined with the observed particle-bound phosphorus distributions suggest that phosphate concentrations along the Delaware Estuary may be partially ‘buffered’ by aluminum and iron oxide phases.  相似文献   

Dynamics of ship collisions     

Martin J. Petersen 《Ocean Engineering》1982,9(4):295-329

This paper described a procedure for simulation of the outer dynamics in ship collisions.The simulation procedure is derived using the transient equations for the horizontal motion of a ship. The hydrodynamic forces acting on the ships' hull during the collision are calculated by a strip method, where the forces acting on each section are described by means of unit response functions. These functions are determined by cosine transformation of the sectional dampings. The sectional added masses and dampings, and thereby also the sectional unit response functions, are calculated by an approximate method. The deformations of the slip structures during the collisions are modelled as non-linear springs.The resulting system of non-linear equations is solved using a numerical time-integration procedure.A number of different collision situations are simulated by means of the procedure.  相似文献   

Rapid visualization of plankton abundance and taxonomic composition using the Video Plankton Recorder     

Cabell S. Davis  Scott M. Gallager  Martin Marra  W. Kenneth Stewart 《Deep Sea Research Part II: Topical Studies in Oceanography》1996,43(7-8)

Traditional methods for determining spatial distributions of planktonic taxa involve net, pump, and bottle collections followed by the tedious and time-consuming task of plankton sample analysis. Thus, plankton ecologists often require months or even years to process samples from a single study. In this paper, we present a method that allows rapid visualization of the distribution of planktonic taxa while at sea. Rapid characterization of plankton distributions is essential in the dynamic physical environment, where biological and physical patterns can change quickly. Such a “sample-and-observe” capability is necessary for mapping ephemeral features (such as patches, eddies, jets, plumes) and determining appropriate locations to conduct more localized sampling, including in situ observational studies. We describe the techniques used in imaging the plankton, analyzing the video, and visualizing the data. We present an example of at-sea data analysis conducted aboard R.V. Columbus Iselin on Georges Bank in May 1994 and visualizations of the 3-dimensional distribution of selected planktonic taxa in a 2 × 2 km × 90 m volume of seawater. A video of the image processing and visualization is included on the CD-ROM accompanying this volume and is an essential part of this paper.  相似文献   

Community turnover provides insight into variable invertebrate recovery between restored streams with different integrated catchment management plans     

Sharon Elizabeth Graham  John Martin Quinn 《新西兰海洋与淡水研究杂志》2020,54(3):467-489

ABSTRACT

Understanding temporal patterns in restored environments is important for identifying potential barriers to recovery and improved management of degraded habitats. In this paper, we use temporal beta diversity analyses to compare invertebrate community recovery trajectories in three restored agricultural stream sites under different integrated catchment plans, a native forest reference site, and two unmodified pasture control stream sites over 24 years. The restored sites diverged from their initial community composition over time and became more similar to the reference site community, which was relatively stable over time. Variation partitioning showed that prior to restoration beta diversity was primarily associated with environmental and spatial drivers, whereas post-restoration beta diversity was more influenced by temporal and environmental drivers, including changes in substrate size, fine sediments, water clarity, and nutrients, as well as temperature and flow regime. Species’ contributions to beta diversity varied between sites and years, with sensitive EPT taxa contributing more in reference and control sites. However, contributions of some EPT species, particularly mayflies, increased in restored sites post-ICM. In summary, after nearly two decades of ICM, restored stream sites show recovery towards reference conditions, yet differences persist, indicating that rehabilitation may take longer, depending on the restoration goals.  相似文献   

Undular tidal bore dynamics in the Daly Estuary, Northern Australia   总被引：7，自引：0，他引：7  

Eric Wolanski  David Williams  Simon Spagnol  Hubert Chanson 《Estuarine, Coastal and Shelf Science》2004,60(4):629-636

Measurements in the macro-tidal Daly Estuary show that the presence of an undular tidal bore contributed negligibly to the dissipation of tidal energy. No recirculation bubble was observed between a trough and the following wave crest in the lee waves following the undular bore. This differs to stationary undular bores in laboratory experiments at larger Froude numbers where a recirculation bubble exists. Secondary motions and the turbulence generated by the undular bore had no measurable influence on the sediment transport. This situation contrasts with the intense sediment resuspension observed in breaking tidal bores. The tidally averaged sediment budget in the Daly Estuary was controlled by the asymmetry of tidal currents. The undular bore may widen the river by breaking along the banks that it undercuts, leading to bank slippage. A patch of river-wide macro-turbulence of 3-min duration occurred about 20 min after the passage of the bore during accelerating tidal currents.  相似文献   

Fast static correction methods for high-frequency multichannel marine seismic reflection data: A high-resolution seismic study of channel-levee systems on the Bengal Fan     

Martin Gutowski  Monika Breitzke  Volkhard Spieß 《Marine Geophysical Researches》2002,23(1):57-75

Very high-frequency marine multichannel seismic reflection data generated by small-volume air- or waterguns allow detailed, high-resolution studies of sedimentary structures of the order of one to few metres wavelength. The high-frequency content, however, requires (1) a very exact knowledge of the source and receiver positions, and (2) the development of data processing methods which take this exact geometry into account. Static corrections are crucial for the quality of very high-frequency stacked data because static shifts caused by variations of the source and streamer depths are of the order of half to one dominant wavelength, so that they can lead to destructive interference during stacking of CDP sorted traces. As common surface-consistent residual static correction methods developed for land seismic data require fixed shot and receiver locations two simple and fast techniques have been developed for marine seismic data with moving sources and receivers to correct such static shifts. The first method – called CDP static correction method – is based on a simultaneous recording of Parasound sediment echosounder and multichannel seismic reflection data. It compares the depth information derived from the first arrivals of both data sets to calculate static correction time shifts for each seismic channel relative to the Parasound water depths. The second method – called average static correction method – utilises the fact that the streamer depth is mainly controlled by bird units, which keep the streamer in a predefined depth at certain increments but do not prevent the streamer from being slightly buoyant in-between. In case of calm weather conditions these streamer bendings mainly contribute to the overall static time shifts, whereas depth variations of the source are negligible. Hence, mean static correction time shifts are calculated for each channel by averaging the depth values determined at each geophone group position for several subsequent shots. Application of both methods to data of a high-resolution seismic survey of channel-levee systems on the Bengal Fan shows that the quality of the stacked section can be improved significantly compared to stacking results achieved without preceding static corrections. The optimised records show sedimentary features in great detail, that are not visible without static corrections. Limitations only result from the sea floor topography. The CDP static correction method generally provides more coherent reflections than the average static correction method but can only be applied in areas with rather flat sea floor, where no diffraction hyperbolae occur. In contrast, the average static correction method can also be used in regions with rough morphology, but the coherency of reflections is slightly reduced compared to the results of the CDP static correction method.  相似文献