Monitoring the marine environment operational practices in Europe

A survey of existing environmental monitoring networks operated in European waters and a review of their main characteristics has been completed. Individual questionnaires have been filled out by persons in charge of operations enabling gathering of up-to-date, accurate information about equipment used and actual operational practices. A map of the location of these networks is shown and a table gives their main characteristics. These data have been used to conduct the analysis of practices employed to maintain these installations. The various difficulties met by operators as well as the costs of these operations are analysed. Methods and procedures are specific to the geographic situations and to the physical characteristics of the monitored sites. The means and resources used for maintenance operations and the related costs are strongly dependent on the distance between the monitoring site and the closest harbour (logistic bases). In the same way, the frequency of on-site interventions are heavily dependant on the bio-productivity of the surrounding environment, bringing a heavy constraint on the choice of the technique for biofouling prevention. Last but not least, the level of data quality seems to be related to the method- ology used for maintenance (both procedure and frequency). The choice of the archi- tecture of measurement systems is also an important factor in the efficiency of the systems.