What 684 items per 100 metres really tells us

A large drop, still a large number

The Joint Research Centre's 2025 trend report puts the median amount of macro-litter on Black Sea coastlines at 684 items per 100 metres for 2020 to 2021. The baseline for 2015 to 2016 was 973 items per 100 metres, a 30% reduction. The figure is still far above the agreed EU threshold value of 20 items per 100 metres.

Those are regional medians from selected monitored beaches. They are not a score for every beach in Bulgaria. The JRC normalised national monitoring data before calculating the trend, so a bag count from one afternoon cannot be compared with it.

The unit is part of the result

Commission Decision 2017/848 defines the coastline measurement for marine litter as the number of items per 100 metres. The unit makes repeat visits and comparisons possible. It also exposes weak comparisons. A 50-metre cleanup and a 200-metre cleanup should not be placed side by side without recording their lengths.

A 2024 original study by researchers at the Institute of Oceanology, Bulgarian Academy of Sciences, used this approach across 45 Bulgarian beaches. The study surveyed each site in four seasons during 2023. It reported 753 plus or minus 97 items per 100 metres on average, with artificial polymer materials making up 88.62% of the total.

What a cleanup number can and cannot do

• Choose a fixed shoreline segment and save its Garbamons pin before collection starts.
• Record the segment length and the part of the beach covered, from the water edge to the back of the beach.
• Count item categories before putting them into bags. Use the JRC Joint List when you want records that can be compared later.
• Write the date, season, and whether the count happened before or after a cleanup.
• Keep the total number of bags separate from the number of counted items.

Make a local series

The European Environment Agency warns that Marine LitterWatch records are dynamic, reflect the effort of participating communities, and need additional handling before they are used for statistical analysis. That is a useful rule for local reporting too. A pin can document a place without pretending that one afternoon proves a trend.

Return to the same segment after a high-use period or a major weather event. Attach the next count to the same place. One point is a report. A series can show whether the place is changing.

Sources

• European Commission Joint Research Centre: European Coastline Macro Litter Trends 2015 to 2021

  Official 2025 trend analysis. Reports Black Sea medians of 973 items per 100 metres in 2015 to 2016 and 684 in 2020 to 2021. (LINK_ONLY)

• European Commission Joint Research Centre: A European threshold value and assessment method for macro litter on coastlines

  Explains the precautionary EU threshold value of 20 items per 100 metres. (LINK_ONLY)

• Commission Decision (EU) 2017/848

  Official Marine Strategy Framework Directive criteria and measurement units for coastline litter. (LINK_ONLY)

• Bekova and Prodanov, 2024, Frontiers in Marine Science

  Open-access original research covering 45 Bulgarian beaches and four seasonal surveys in 2023. (OPEN_REUSE)

• European Environment Agency Marine LitterWatch data viewer

  Explains the dynamic nature of the data and why community records are illustrative rather than automatically statistical. (LINK_ONLY)

• Joint List of Litter Categories Manual

  EU category list for comparable marine macrolitter monitoring. (LINK_ONLY)