A European Threshold Value and Assessment Method for Macro Litter on Coastlines.

Abstract

The Marine Strategy Framework Directive (MSFD, 2008/56/EC) requires that European threshold values (TVs) for marine litter (descriptor 10) be defined. The MSFD Technical Group on Marine Litter (TG ML) decided to focus on coastline litter (Criterion 1), often referred to as beach litter, in a first step, since for this criterion a monitoring framework is in place and a substantial amount of fit-for-purpose beach litter monitoring data is available at the European scale (see Hanke et al., 2019). This report describes the rationale and method to obtain a European TV for beach litter, as developed by Member States and other experts within the TG ML. It was concluded by TG ML that a TV cannot be based on quantitative ecological and socio-economic harm due to a lack of scientific data on harm caused by marine litter on beaches. Of the remaining options, the use of the 10th percentile value of the total litter abundance dataset from all European beaches in the baseline period 2015-2016 was selected and applied, as it was considered to be sufficiently precautionary while being based on already available beach litter abundances in the EU. The underlying baseline dataset was developed within the TG ML. Calculation of the 10th percentile of the EU baseline dataset resulted in a value of 13 litter items per 100 m of coastline length. Further consideration of the 95% confidence intervals of the TV and assessment value, respectively, led to a final TV of 20 litter items/100 m beach length, which corresponds to the 15th percentile value of the EU baseline dataset. This TV is estimated by experts from TG ML to reduce harm from beach litter to a sufficiently precautionary level. The methodology acknowledges uncertainties in the underlying data which is considered in the proposal. The median assessment value is compared with this TV for compliance checking. It is acknowledged that achieving this TV will require substantial and sustained measures over a longer period. Intermediate targets over time towards the proposed TV are proposed to support the achievement of the TV.