An approach to the integration of beach litter data from official monitoring programmes and citizen science.

Abstract Marine litter on Spanish beaches is assessed through two monitoring programmes: the Official Monitoring Programme of Marine Litter on Beaches (BM-1) developed by the Spanish Ministry for the Ecological Transition and the Demographic Challenge and the Citizen Science Monitoring Programme (BM-7) that provides beach litter data from voluntary clean-up initiatives. So far, the data provided by both programmes have been analysed separately although their integration could improve the assessment of the situation of Spanish beaches regarding marine litter. To this end, this paper studies the possible integration of both datasets through the calculation of a baseline value for marine litter on Spanish beaches. Statistical analysis of data shows that both datasets produce similar values and also integrate in a consistent way to achieve a value of 128 items/100 m as a baseline value for beach litter in Spain.