This visualization product displays the transparency of litter in percent per net per year from research and monitoring protocols. EMODnet Chemistry included the collection of marine litter in its 3rd phase. Before 2021, there was no coordinated effort at the regional or European scale for micro-litter. Given this situation, EMODnet Chemistry proposed to adopt the data gathering and data management approach as generally applied for marine data, i.e., populating metadata and data in the CDI Data Discovery and Access service using dedicated SeaDataNet data transport formats. EMODnet Chemistry is currently the official EU collector of micro-litter data from Marine Strategy Framework Directive (MSFD) National Monitoring activities (descriptor 10). A series of specific standard vocabularies or standard terms related to micro-litter have been added to SeaDataNet NVS (NERC Vocabulary Server) Common Vocabularies to describe the micro-litter. European micro-litter data are collected by the National Oceanographic Data Centres (NODCs). Micro-litter map products are generated from NODCs data after a test of the aggregated collection including data and data format checks and data harmonization.

A filter is applied to represent only micro-litter sampled according to research and monitoring protocols as MSFD monitoring.

To calculate percentages for each transparency, formula applied is: Transparency (%) = (?number of particles of each transparency)*100 / (?number of particles of all transparency) When the number of microlitters was not filled or zero, the percentage could not be calculated.

Standard vocabularies for microliter transparency are taken from Seadatanet's H06 library (https://vocab.seadatanet.org/v_bodc_vocab_v2/search.asp?lib=H06)

Warning: the absence of data on the map doesn't necessarily mean that they don't exist, but that no information has been entered in the National Oceanographic Data Centre (NODC) for this area.