Most marine litter monitoring methods used on beaches focus on macro-litter (>25 mm) only and show shortcomings regarding smaller litter classes (<25 mm), especially at Baltic Sea beaches. Therefore, we used a sand rake method developed for large micro- (2–5 mm), and meso- (5–25 mm) litter to quantify the overall pollution status of Baltic Sea beaches and to test if the method is useful in terms of the requirements of the Marine Strategy Framework Directive (MSFD). Between July 2017 and October 2019, 197 sand rake method surveys were carried out at 35 regions around the Baltic Sea. In total, 9345 litter pieces were found on an area of 10,271 m² of which 69.9% were 2–25 mm in size. Artificial polymers (4921 litter pieces) were predominant (mean 52.7% ± 13.3). Abundance of litter was 0.91 pieces/m² ± 1.50 (median 0.40 pieces/m²). The most common litter were industrial pellets (19.8%), non-identifiable plastic pieces 2–25 mm (17.3%), cigarette butts (15.3%), and paraffin (11.9%). At 15 surveys at the German North Sea island of Sylt the litter abundance ranged from 0.45 pieces/m² (median) to 0.59 pieces/m² ± 0.37 (mean). Here, 69.2% of the litter was 2–25 mm in size and paraffin was predominant (69.2%). Beaches show a high pollution level with large micro- and meso-litter (2–25 mm) and our data can serve as a Baltic-wide pollution baseline. In contrast to the naked eye OSPAR method for macro-litter, the sand rake method is generally applicable on all sandy beaches, both urban and remote. This method also allows for the provision of a full spatial pollution pattern and can serve for assessing the effectiveness of marine litter mitigation measures.

We conducted surveys of Mediterranean beaches in Egypt, Morocco, and Tunisia including 37 macro-litter (> 25 mm) and 41 meso-litter (5–25 mm) assessments. Our study identified key litter items and assessed pollution sources on urban, semi-urban, tourist, and semi-rural beaches. Macro-litter concentration averaged 5032 ± 4919 pieces per 100 m or 1.71 ± 2.28 pieces/m², with higher values observed on urban (mean 2.63 pieces/m² ± 3.03) and tourist (mean 1.23 pieces/m² ± 0.91) beaches. Similarly, urban (mean 9.91 pieces/m² ± 12.70) and tourist beaches (mean 5.32 pieces/m² ± 4.48) revealed elevated levels of meso-litter contamination, particularly in the upper third of the beach, which contained the highest quantities both in terms of number (51%) and weight (50%). 55% of the macro-litter and 35% of the meso-litter originated from human shoreline activities and poor waste management. Given the width of some beaches and their high levels of pollution, the standard 100 m macro-litter approach was impractical. To enable cost-effective, long-term monitoring, we adapted it to a faster 10 m transect approach, which provided reliable data on the top 25 litter items, accounting for 82% of beach pollution. Our Sand Rake method effectively quantified pollution on both cleaned and uncleaned beaches, addressing the often neglected meso-litter size fraction. The high pollution levels, top litter items, and identified sources indicate that beach cleaning alone will not solve the pollution problem. Efforts to raise environmental awareness, enhanced waste management, and law enforcement are needed to improve the situation in a sustainable way.

The macro-litter (plastic) sea-bottom pollution of 14 city harbors and marinas in North Africa and in the western Baltic Sea was investigated using a new simple mobile underwater camera system. The study was complemented by a harbor-manager survey and 3D hydrodynamic transport simulations. The average pollution in German marinas was 0.1 particles/m² sea floor (0.04–1.75). The pollution in North African marinas on average was seven times higher (0.7 particles/m²) and exceeded 3 particles/m² in city-center harbors. The resulting > 100,000 litter particles per harbor indicate the existence of a problem. At 73–74%, plastic particles are dominating. Existing legal and management frameworks explain the lack of plastic bottles and bags on sea floors in Germany and are one reason for the lower pollution levels. Items that indicate the role of untreated sewage water were not found. Harbor festivals seem to be quantitatively irrelevant for open sea-bottom pollution. Our method tends to underestimate the pollution level. Model simulations indicate that storms can cause litter reallocations and sediment cleanings. However, marina sea-floor monitoring is recommendable because it addresses pollution hotspots, is cost-effective and takes place close to emission sources. Further, the effectiveness of land-based pollution-reduction measures can easily be assessed.

Sandy beaches along the North African Mediterranean coast face significant challenges due to accumulating human-made debris (marine litter) and natural debris (beach wrack). Addressing these issues requires awareness of pollution and the ecological relevance of beach wrack, along with stakeholder involvement. This study quantifies beach litter pollution and identifies sources in Tunisia, Morocco, and Egypt, serving as a basis for ecosystem service assessments and further integration into the implementation of mitigation measures. High levels of plastic litter were found, ranging from 1565 to 7778 pieces per 100 m of beach length. Shoreline activities, tourism, and poor waste management were identified as the main sources of litter, with single-use plastics accounting for 41.1% of the debris. Further objectives include providing a list of suitable ecosystem services and developing management scenarios. Local stakeholders’ perceptions of the impact of marine litter and beach wrack on ecosystem services were assessed using a scenario approach and different formats (i.e., stakeholder workshop, interviews, teaching). Stakeholders highlighted the negative impact of marine litter on cultural services, while beach wrack was perceived positively for regulating and maintenance services. This approach enhances awareness, interest, and knowledge in data-scarce regions, serving as a valuable tool for stakeholder engagement, elicitation of stakeholder knowledge, and teaching (i.e., learning tool). Limitations include the subjectivity of the results, limited participant reach, and dependence on stakeholder knowledge. Integrating stakeholder-based ecosystem service assessments into measure planning and decision making is essential for effective litter management and beach conservation efforts.