How to link the definition with monitoring and assessment activities?
Despite positive pan-European developments in defining eutrophication, it is still unclear what an undesirable disturbance is. The phrase is open to interpretation and should be reconsidered. We suggest that an undesirable disturbance in ecological terms is understood as an unacceptable deviation from reference conditions . We realize that an unacceptable deviation is also open to interpretation, but the advantage is 2-fold. First, the definition will be linked to the WFD implementation process, and second, reference conditions sensu the WFD will be the starting point. We also suggest inclusion of primary production measurements in monitoring systems. These should be based on a reasonable and cost-effective approach, that is, monitoring networks should be stratified and based on two types of stations: (i) intensive stations/areas where many indicators are monitored with high frequency and (ii) mapping stations where a few indicators are monitored with lower frequency. This kind of stra
