Micro litter - Spatial distribution of litter density normalized per km² - Research and monitoring protocols 2011/2023 v2025

This visualization product displays the spatial distribution of litter density normalized per km² 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.
Densities were calculated for each net using the following calculation:
Density (number of particles per km²) = Micro-litter count / (Sampling effort (km) * Net opening (cm) * 0.00001)

When the number of microlitters or the net opening was not filled, it was not possible to calculate the density.

The spatial distribution was then determined by calculating the weighted average of the densities in each cell using the following formula:
Weighted average of the cell c (number of particles per km²) = ( (Sampling effort (km) of net 1 * Density (number of particles per km²) of net 1) + … + (Sampling effort (km) of net N * Density (number of particles per km²) of net N) ) / ∑ Sampling effort (km) of all nets in the cell c.

Percentiles 50, 75, 95 & 99 have been calculated taking into account data for all years.

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

This work is based on the work presented in the following scientific article:
O. Gerigny, M. Brun, M.C. Fabri, C. Tomasino, M. Le Moigne, A. Jadaud, F. Galgani, Seafloor litter from the continental shelf and canyons in French Mediterranean Water: Distribution, typologies and trends, Marine Pollution Bulletin, Volume 146, 2019, Pages 653-666, ISSN 0025-326X, https://doi.org/10.1016/j.marpolbul.2019.07.030.