Development of a sliding device for extended measurements in coastal waters

Extensive measurements of main sea water parameters (e.g. temperature, salinity, dissolved oxygen, nutrients, bacterial abundance, etc) are required to investigate the marine environment, both to evaluate its state and to quickly detect possible perturbations (arrival of pollutants, anthropogenic contaminants, etc). Traditional observing methods cannot offer the flexibility and cost effectiveness needed for extensive monitoring and water quality assessment in coastal areas where important health and economic issues are involved (e.g. aquaculture, tourism). As part of the MFSTEP program (EU FP5) a new device was designed and built for pelagic use, the SAVE (Sliding Advanced VEhicle), able to perform continuous profiles of physical and optical measurements on the upper 200 m of the water column. The original system consists mainly of a depressor, towed at a fixed depth, using a cable on which the main unit slides. Both the depressor and the sliding unit can be equipped with various kinds of sensors. The new goal was to obtain a coastal version, to be towed from small boats. A smaller prototype is now under development and testing, and it is able to be towed by a very small (8-10 m) boat, like those commonly used in aquaculture plants, and also fitted with modular water samplers for bacterial or chemical determinations. The paper gives some first results of this development.