This paper presents a method developed to quantify three-dimensional energy dispersive spectrometry (3D EDS) data with voxel size smaller than the volume from which X-rays are emitted. The influence of the neighboring voxels is corrected by applying recursively a complex quantification, improving thereby the accuracy of the quantification of critically small features. The enhanced quantification method is applied to simulated and measured data. A systematic improvement is obtained compared with classical quantification, proving the concept and the prospect of this method.

The paper describes the main drawbacks in the application of conventional acoustics in shallow waters, and reviews the advantages and limitations that existing multibeam sonar present in these ecosystems. New techniques and methods for adapting multibeam sonar to shallow waters are proposed and discussed. A method for analysing acoustic data from shallow waters through image analysis process is presented and some examples are considered. The results show that scattered fish can be observed individually and counted, and that schools are described in their morphology and behaviour. From these results an ‘ideal’ acoustic device is defined: a sonar operating at more than 400 kHz with a coverage of at least 120° in one direction and, depending on the needs of the user, 15° or 1° (which can be modified easily) in the perpendicular plane. The beam opening–angle is 0.5° in the centre beam, increasing to 1.0° at the 60° steer–angle, giving a total of 240 beams. Multibeam sonar data could be used for several purposes in shallow waters, in particular to estimate fish density and biomass, and study spatial and temporal behaviour of fish.