Feeding Habits of Trisopterus minutus capelanus (Gadidae) Off the Eastern Coast of Spain (Western Mediterranean)

Abstract. The stomach contents of poor cod, Trisopterus minutus capelanus (Lacepède), were taken at monthly intervals off the eastern coast of the Gulf of Valencia (Spain). A total of 1276 were analyzed to determine diet according to fish size and season. The basic food consists of crustaceans (Mysidacea and Decapoda) and teleosts. Feeding habits varied with size: decapods and fishes were more abundant in the stomachs of larger specimens. Little seasonal variation in food habits was recorded.     

On non-causal impulse response functions related to propagating water waves

Particular attention is drawn to the non-causality of two impulse response functions, one of which relates the excitation force on an immersed body to the incident wave elevation at the body's reference position, while the other relates the incident wave elevations at two different positions along the line of wave propagation. An explanation is proposed for the non-causality of the impulse response functions, in spite of the fact wave propagation is a causal process. An indication is given of how far ‘upstream’ the incident wave elevation should be measured in order to be able to know, with reasonable accuracy, the current heave excitation force on a floating truncated cylinder with vertical axis, given current and past wave-elevation measurements. This provides a method for wave prediction, which is required for optimum control of the oscillation of the immersed body.     

Preliminary report on radionuclide concentrations in the bottom waters at the entrance of Wakasa Bay with special reference to the Japan Sea Proper Water

Marked fluctuation of concentrations of⁹⁰Sr and¹³⁷Cs was observed in the bottom waters at the entrance of Wakasa Bay during 1987–1992, and the cause was investigated. The concentrations of⁹⁰Sr and¹³⁷Cs in the bottom waters were significantly low when the upper level of the Japan Sea Proper Water (JSPW) was high and covered the sampling depth, but high when the upper level of the JSPW was low. The cause of the fluctuation observed in the bottom waters is, therefore, suggested to be the vertical fluctuation of the upper level of the JSPW on the shelf slope, which has been little described before.     

Carbon Isotope Geochemistry of the Orinoco Basin

Stable carbon isotope ratios have been used to study the sources of particulate organic carbon (POC) and total dissolved inorganic carbon in the Orinoco Basin. The isotopic composition of total dissolved inorganic carbon shows a range of from -8·1 to -23·0 ppt, an indication of dominance of biological processes. The isotopic composition of POC exhibits a range of from -24·1 to -34·6 ppt with little seasonal variation. The isotopic evidence indicates that the POC is predominantly of terrestrial origin rather than a result of in situ planktonic production. The similarity of isotopic composition of POC and coastal sediments suggests that riverine organic detritus has been transported 30-50 km offshore in a direction parallel to the Orinoco river channel.     

A residual analysis method for quantitative comparison of spatial data from the Iceland-Faeroes Front

A spatial statistical method has been developed from the well-known Kriging technique in geostatistics, as a way of providing quantitative comparison between a pair of spatial data sets, and a measure for such a comparison. This residual analysis method is applied to oceanographic data in order to compare Iceland-Faeroes Front (IFF) model predictions against appropriate field observations, with an aim to assess the IFF model performance and its prediction accuracy. The method is also used to evaluate the model-generated dynamical variability within the model predictions, as well as the natural variability within the frontal observations. From the results, it has been found that the IFF model is highly robust, and gives better predictions at depth 150–350 m than elsewhere. Within such a depth (i.e. 250–350 m), there is also evidence to suggest that the main frontal region is most active above the IF Ridge. The natural variability obtained from the observations appears to be comparable to the model-generated dynamical variability after 20 days of integration, indicating a certain degree of accuracy in the model predictions. The method reported in this paper could also be extended for further use in model data assimilation. Thus, the work not only demonstrates how spatial statistics can be applied to oceanographic data, but also opens up new statistical tools for data handling in ocean modelling.     

Video observations of marine gravel transport

In an analysis of video observations of gravel transport in the West Slent, UK, collective and individual characteristics of 458 bursts of bedload have been examined and the transport velocity and distance of 1680 individual particles in a consecutive succession of burst events determined. Infrequent, long duration, high stress events account for 60% of total transport in only 24% of the total time with the mean free path and transport velocity for particles being 0.16 m and 0.22 m/s, respectively. Clear links between intense intermittent turbulence and bedload transport revealed in this study, suggest progress in modelling requires a clearer understanding of near bed flow structure.     

Modern swathe sounding and sub-bottom profiling technology for research applications: The Atlas Hydrosweep and Parasound Systems

This chapter describes two separate but complementary research echosounder systems originally developed by Krupp Atlas Elektronik GmbH for the new German oceanographic research vessel Meteor.The Hydrosweep is a Hydrographic wide-swathe sweep survey echosounder for both shallow and deep water applications providing accurate bathymetric surveys and terrain-following navigation capabilities.The Parasound system is a hull-mounted dual channel parametric narrow-beam deep sea survey and sub-bottom profiling echosounder enabling particularly high vertical and horizontal resolution of seabed features.