Addressing the challenge of marine plastic litter in the Moroccan Mediterranean: A citizen science project with schoolchildren.

In this study, based on data collected by citizen science, we studied the abundance, spatial and temporal distribution of marine litter in three beaches of the Moroccan Mediterranean. A total of 14,042 litter items were collected with an average abundance of 0.58 items/m. The most of litter were composed of anthropic polymeric materials, representing 74 % of the total litter collected. Plastics account for the majority of the items collected and are mainly caps/lids, crisp/sweet packets, plastic/polystyrene, cigarette butts and small plastic bags. Litter abundance displayed significant seasonal differences, with the highest during summer. Tourism and poor waste management practices are the major sources of plastic on the beaches surveyed. The use of the Clean Coast Index (CCI) and the Plastics Abundance Index (PAI) permits the classification of the three beaches in the Moroccan Mediterranean as a "moderately clean" coastal area with a "very high abundance" of plastics. In addition, the Hazardous Items Index (HII) allows classification of the region as highly polluted by hazardous litter. Best management measures are needed to promote the environmental quality of the beaches of the Moroccan Mediterranean.