Coastal and estuarine systems can retain floating macroplastics before they reach the open sea, yet these environments are often underrepresented in marine litter monitoring and assessments. We investigated floating macroplastic retention under six wind conditions and over a year in two semi-enclosed Baltic Sea systems (the Warnow Estuary and Greifswald Bay). We used high-resolution (20m and 200m) 2D hydrodynamic models with Lagrangian particle tracking, adding retention based on entrapment observed in drifter experiments in the reed belts. Model results were compared to in situ surface drifter trajectories in the Warnow Estuary. Drifter trajectories under two contrasting wind conditions closely matched the modeled accumulation patterns and travel times. Annual retention of simulated particles exceeded 80% in both systems, while short-term (72h) retention reached up to 100% in the Warnow Estuary. Reed belts were the primary retention zones, whereas artificial structures also contributed to retention. Extrapolating our results to the Baltic Sea, macroplastic retention in coastal and estuarine systems may be at least 50% lower than previous estimations (38 million items compared to the 76 million items per year reported from previous studies)

Abstract There is an urgent need to address the contribution of mass tourism to coastal litter generation, however, identifying effective, context-specific measures to reduce listed litter remains challenging. This study evaluated 142 beach and tourism ecolabels against a list of 43 litter reduction measures to assess their potential and effectiveness as tools for beach macrolitter reduction. A total of 24 ecolabels addressed litter, applicable in different countries. Ecolabels included 7–53% of litter reduction measures, with only two ecolabels exceeding 50%. Benefits and challenges of ecolabel implementation were explored taking Morocco, Tunisia and Egypt as case study areas, and considered aspects like current ecolabel implementation, state of pollution, and ecolabel acceptance by managers and beachgoers. Moroccan beaches showed the lowest pollution levels, which may coincide with national efforts on beach litter reduction programs and/or Blue Flag implementation, mandated by the government. Nevertheless, limited spatio-temporal data restricts definitive conclusions in regards to ecolabel effectiveness. In general, ecolabels present limitations to address and reduce the ubiquitous presence of beach macrolitter. They fail to prioritize most effective measures to address top litter items, act at a limited spatio-temporal scale, and focus on criteria compliance rather than environmental outcomes. We recommend ecolabels should (1) integrate effective and context-specific measures informed by local litter monitoring data, (2) include litter thresholds in line with international legislation to assess litter reduction over time, (3) include short-term, low-effort actions as well as support long-term policy strategies, (4) incorporate indices to monitor progress, and (5) engage stakeholders with different backgrounds in ecolabel implementation.

The Ecosystem Service framework is essential for understanding the role of Marine Protected Areas (MPAs) in delivering conservation benefits and societal goods such as fisheries. A perception analysis was conducted to capture the views of 33 experts on MPA-associated ecosystem services. Moreover, using The MPA Guide, we applied a scenario-based approach to assess the potential impact of different degrees of protection (i.e., fully, highly, lightly, and minimally protected levels) on fisheries-related ecosystem services. An expert-based evaluation explored the influence of these protection levels on fisheries-related ecosystem services across two prospective timeframes, set at 3- and 7-years post-implementation. Findings indicate a broad consensus on the perceived importance of cultural services attributed to MPAs. Provisioning MPA-associated ecosystem services are moderate, and their relevance varies by experiential and disciplinary backgrounds of experts. Fully and highly protected levels were perceived as the most effective in enhancing fisheries-related ecosystem services, particularly through increased fish abundance, individual size, and biomass. While provisioning fisheries-related ecosystem services were clearly perceived as increasing over time, especially under higher protection levels, the trends for regulation/maintenance and cultural fisheries-related ecosystem services were more subtle. This study highlights the need for adaptive protection strategies that account for temporal scales, reinforcing the role of long-term monitoring frameworks that capture both socioeconomic and social-ecological outcomes. Moreover, by introducing a qualitative cost-effective expert judgment, this methodology can be implemented in data-poor contexts such as the Mediterranean region. The findings provide valuable insights for policymakers and MPA planners striving to implement the EU 2030 Biodiversity Strategy in the Mediterranean Sea in terms of design, zoning, and governance of strictly protected MPAs that are both ecologically effective and socially acceptable.

Excessive riverine nutrient inputs are a main driver of eutrophication in marine waters. Thus, identifying areas most affected by river plumes is a key challenge for effective water quality management. Transitional waters, which are affected by river plumes, but also have open sea characteristics, are usually merged with larger open sea assessment units. This leads to non-representative spatial units, whose unreliable assessment results cannot support the implementation of measures in order to improve the water quality. An example for this mismatch is the Oder (Odra) river plume area in the southern Baltic Sea. Due to the missing separation of the river plume area from the open sea waters, its management is suffering from the too coarse classification. We apply two model-based techniques to study the spatial and temporal variability of the Oder river plume and to follow the distribution of its nutrients and pollutants in the sea. Based on the results, we propose an improved layout for the assessment unit that better captures the spatial heterogeneity. By applying a one-way ANOVA, we show that the best size and shape of the river plume assessment unit depend on the water quality indicator being used. A smaller assessment unit near the river mouth is best for dissolved nutrients, while an area nearly four times larger is better, if chlorophyll-a is assessed. Furthermore, thresholds defining the Good Environmental Status (GES) are derived for the new unit and the remaining offshore area. These thresholds align with natural gradients and are consistent with existing GES targets already adopted by the member states of the Baltic Marine Environment Protection Commission.

The Oder/Szczecin Lagoon is one of the largest Baltic Sea lagoons and is subject to very high nutrient loads from the Oder/Odra River. For our study, we employ a modified, high-resolution 3D ecosystem model specifically adapted for this shallow lagoon. The model demonstrates stable and reliable performance over 25 years of simulation (1995–2019), enabling a detailed assessment of lagoon processes under various scenarios. Our model simulations indicate that changes in riverine nutrient inputs have an immediate impact on the lagoon’s water quality, affecting parameters such as phytoplankton biomass and water transparency. Hypoxia is a prevalent phenomenon, affecting most parts of the lagoon which promotes internal eutrophication. On average, the lagoon retains 12 % (253 t yr−1) of the phosphorus and 40 % (17 278 t yr−1) of the nitrogen riverine inputs. The primary sink process for phosphorus is sediment burial, and for nitrogen, it is denitrification. Nitrogen retention decreases with increasing riverine loads, dropping to around 30 % during years with exceptionally high inputs. In contrast, phosphorus retention is independent on loads. The nutrient retention capacity of the lagoon has significant implications for Baltic Sea eutrophication but is not currently accounted for in major policies and Baltic Sea models. Although recent nutrient loads from the Oder River comply with policy targets, such as the Baltic Sea Action Plan’s maximum allowable inputs and Germany’s river targets, these levels are insufficient to improve the lagoon’s ecological state sufficiently. The Oder Lagoon remains in a highly eutrophic condition, making the achievement of a good ecological status unlikely under the current management targets.

Beach wrack can accumulate in large quantities on beaches and is often regarded as a nuisance by beach managers, which is removed for the sake of tourists. The litter entangled in beach wrack can prevent further use of this natural resource. However, not much is known about the litter quantities in beach wrack nor their input paths. We applied an easy-to-use method for beach wrack monitoring in two case studies, in the southern Mediterranean Sea and the eastern German Baltic Sea. Our objective was to investigate whether litter found in beach wrack provides an indication for the input path “sea to beach” and whether there is a correlation between beach wrack and litter quantities, allowing an extrapolation of litter quantities to longer stretches of coastline based on beach wrack cover. The results of 14 surveys in Germany and 6 surveys in North Africa do not provide sufficient evidence for the input path “sea to beach” for litter in beach wrack nor for a correlation between beach wrack and litter quantities. However, we show that litter quantities in beach wrack at the waterline can be 3–13 times higher than what is found on bare sand and that old, scattered beach wrack may entrap 181 times more litter, evidencing that it serves as a sink of litter on beaches. We recommend further large-scale studies, targeting freshly deposited wrack, to gain more information on beach wrack litter quantities and input paths, and to support better decision-making on beach wrack management.

Marine litter is a critical environmental issue, with beach litter being its most visible indicator. Despite severe pollution on Mediterranean beaches, Tunisia currently lacks a national beach litter monitoring program. To address this gap and support the development of such a program, particularly at pollution hotspots like urban beaches, we conducted a one-year study on six Tunisian beaches. We employed an innovative, accelerated multiple 10 m transect method tailored to highly polluted beaches, focusing on macro-litter (>2.5 cm). This method significantly reduces survey time compared to the standard 100 m approach while maintaining comparable pollution metrics, offering a practical and efficient solution for areas with high litter density. Our findings reveal an average litter density of 1.01 ± 1.08 pieces/m2, with higher pollution in urban areas. Based on the Clean Coast Index (CCI), two beaches were classified as extremely dirty, one as dirty, two as moderately clean, and one as clean. Plastics (59.2%) and cigarette butts (21.1%) were the most prevalent pollutants, with single-use plastics comprising 52.5% ± 5.3% of total litter. Most of the litter (60.6%) originated from shoreline activities and poor waste management. These findings underscore the urgent need for a long-term national beach litter monitoring program. The integration of our accelerated transect method would enable efficient, effective surveys on highly polluted beaches, providing critical data to address litter sources and support targeted strategies for mitigating pollution and protecting Tunisia’s coastal ecosystems.

Oxygen is a key indicator for assessing the ecological condition of coastal waters, yet current monitoring programs often fail to adequately capture the occurrence and impact of hypoxia, anoxia, and their consequences. In this study, we combine long-term observational data with a 3D ecosystem model and use summer peaks of inorganic phosphorus concentrations as a proxy for anoxic events and subsequent sedimentary phosphorus release. This approach allows us to assess the duration, spatial extent, and ecological impacts of oxygen depletion in the Oder/Szczecin Lagoon, located in the southern Baltic Sea. Mass mortality events of aquatic organisms have been observed in the lagoon, and the model indicates that anoxic conditions frequently occur at a large scale directly above the sediment. However, these events are not captured in standard oxygen measurements, sampling 1 m above the sediment. We suggest a site-specific precautionary value for hypoxia of 8 mg O2/L, when measurements are limited to 1 m above the sediment. Daily and hourly maximum wind speeds can serve as site-specific proxies for oxygen depletion, reflecting changes in water mixing depth and indicating periods of stagnation above the sediment. Altogether hypoxia is still an underestimated problem and modified monitoring and assessment strategies are required and suggested. Anoxic phosphorus release from sediments can result in internal phosphorus loads of up to 1,000 tons per month, significantly exceeding all other external phosphorus inputs to the lagoon. The phosphorus concentration peaks do not permit detailed quantification of these anoxic processes and do not appear to have ecological consequences within the lagoon itself. However, it alters the seasonal pattern of nutrient loading and contributes additional phosphorus to the coastal Baltic Sea during the ecologically critical summer months. Over recent decades, both anoxia and internal eutrophication in the lagoon have shown a declining trend, coinciding with reductions in external nutrient inputs from riverine sources. Consequences on policy implementation and monitoring are discussed.

We conducted 3D ecosystem model simulations over a 10-year period, supplemented by socio-economic data, to evaluate the ecosystem services provided by the large, shallow Oder/Szczecin Lagoon. Our analysis focused on three scenarios reflecting the progressive deepening of the navigational waterway across the lagoon: from 6 m (1880) to 10.5 m (1984) and finally to 12.5 m (2023). For the 10.5 m scenario, the total value of all six ecosystem services was estimated at EUR 272 million/year, or approximately EUR 0.4 million/year/km2. The individual contributions of each ecosystem service were as follows: nitrogen retention, EUR 166 million/a; phosphorus retention, EUR 5 million/a; carbon storage, EUR 0.4 million/a; active recreation, EUR 61 million/a; landscape aesthetics, EUR 36 million/a; wild fish catches, EUR 3.2 million/a; and transportation, EUR 32 million/a. Among these, denitrification emerged as the most economically important process, valued at EUR 178 million/year, or EUR 0.26 million/year/km2. Regulating ecosystem services displayed substantial interannual variability and pronounced seasonality. Additionally, the two parts of the lagoon, Kleines Haff (Germany) and Wielki Zalew (Poland), exhibited distinct patterns. Our model indicates that channel deepening enhances sediment burial and significantly increases phosphorus and carbon retention. However, the associated increase in connectivity to the Baltic Sea appears to have a minor effect.

Single-use plastic (SUP) tableware is one of the top ten items found on beaches worldwide. Bio-based, biodegradable and compostable tableware have emerged as a popular alternative to replace SUPs, however, often used without deep consideration to disposal needs and environmental impact, which are key aspects to ensure litter reduction. This study critically evaluated the usage of six bio-based tableware materials at coastal festivals, examined the gaps between policy regulations and waste management in Germany, Lithuania, Chile and Tunisia, assessed the social perception, awareness and acceptance towards material alternatives, and investigated the materials disintegration under real environments: estuarine water and an industrial composting facility. Our policy analysis revealed that whilst the majority of policies are designed to phase out conventional SUPs, the available infrastructure in the study areas is not equipped to handle alternative materials. Our public survey revealed a general lack of awareness regarding degradability, disposal requirements and ecological footprint of the different materials, indicating knowledge gaps and confusion in the public which could result in improper disposal and littering. Finally, the disintegration experiments demonstrated that only tableware made of palm leaves, cardboard, and sugar cane bagasse fully disintegrated in estuarine water over 1 year, while only PLA tableware fully disintegrated in industrial compost within 12 days, demonstrating that disintegration is highly environment-specific. Our findings bring together important aspects that have not been analyzed in conjunction before and highlight research gaps that become relevant in the revision of the International Plastics Treaty.

Estuaries account for 88% of the global coastline and act as filters for water, sediments and particles (Dürr et al. 2011) and may act as important pathways of plastic pollution. Recent studies suggested that rivers can contribute between 1.15 – 2.41 million tons of plastic per year globally (Lebreton et al. 2017) or 307 and 925 million items per year from Europe alone (Gonzalez-Fernández et al. 2021). However, the processes of transport and retention at rivers, estuaries and beaches are still poorly understood. Recent results from Schernewski et al. (2024) showed that floating plastics released at a city harbor at the beginning of the Warnow estuary (Germany) were trapped in reeds or beaches within 6 days, with only 0.4% transported to the Baltic Sea (11 km) during storms, while sinking plastics accumulated near the source during calm winds (7 m/s) but were resuspended and transported up to 4 km away during storms (< 20 m/s). However, this study considered only one emission location and there is still a knowledge gap regarding the role of item size and density, as well as the emission locations from multiple litter sources, and thereby the retention potential at coastlines and seafloor.In this study, we investigate the emission, transport and retention of plastics in the Warnow estuary, Germany, an exemplary estuary exposed to urban areas, harbor activities, tourism and other land-uses, using a highly resolved 3D hydrodynamic model of 20 m and a Lagrangian particle tracking approach using the Ocean Parcels framework. Emission source locations were defined with GIS. First simulations considered the emission of particles from the tourism and recreation sector over 10-days, with 1000 particles released per point. The results showed for emission sources closer to the estuary opening and the beach, 68% of particles were retained, whereas for particles released at the harbor and urban area (beginning of the estuary), 92% were trapped on beaches or reed belts, with the majority beaching within the first 2 days only 3.5 km away from the source. These results already indicate that the emission of plastics may be overestimated since few studies take into account emission location and retention dynamics.Building upon these learnings we aim to i) provide a detailed emission budget for different sources of plastics at the Warnow estuary and ii) assess the influence of item size and density in the transport and retention of particles. This high resolution model together with the emission approach shall provide a more comprehensive assessment of emission, transport and accumulation of plastics and contribute to the understanding of the plastic budget at other estuaries as well as for the elaboration of effective mitigation strategies based on specific accumulation hotspots and emission sources.

Knowledge of the structure and spatial distribution of coastal water habitats is crucial for understanding coastal water systems. However, spatial habitat data are largely lacking, hampering ecological and ecosystem service assessments as required by EU policies. Mapping the structure, spatial distribution, and temporal dynamics of macrophytes is a particular challenge. In this study, we combined long-term macrophyte data with remote sensing methods (i.e., aerial and underwater drones, as well as SENTINEL-2 data) to assess their potential for spatial macrophyte monitoring and habitat-based ecosystem service assessments, in which ecosystem services were linked to habitats using the expert-based Baltic Ecosystem Service Potential Matrix. Greifswald Bay in the German Baltic Sea served as the case study for this research. Our aerial drone detected macrophytes up to a depth of 3 m that could be integrated into the existing macrophyte monitoring scheme of the Water Framework Directive. Reliable data from SENTINEL-2 were only obtained in optically shallow waters and could therefore only be used as proxy indicators to assess changes at a water body level. Despite the uncertainties and inaccuracies of the SENTINEL-2-based macrophyte maps, they were crucial for filling data gaps and enabled a spatially differentiated ecosystem service assessment for Greifswald Bay. However, we have shown that the commonly used matrix approach does not allow for the assessment of spatiotemporal changes at the water body level and is thus not suitable for supporting coastal and marine policy implementation.

The coastal Oder/Szczecin Lagoon is subject to multiple external changes, particularly the reduction in external nutrient loads and the impacts of climate change, including rising temperatures and more frequent heatwaves. By combining monitoring data covering the past 40 years with 3D ecosystem modelling, we assess changes in phytoplankton abundance and diversity across different temporal scales, ranging from long-term trends to the short-term effects. Despite strong reductions in external nutrient loads, neither the average annual phytoplankton biomass nor the long-term species composition changed significantly, although extreme summer blooms appear to have decreased. In summer, cyanobacteria, usually dominated by Microcystis, can reach a relative biovolume of up to 90%. Bacillariophyceae (diatoms) contribute up to 72% of the annual relative biovolume and dominate in spring. Both interannual and short-term variability in phytoplankton biomass and composition are pronounced. Heat- and coldwaves show no consistent immediate effects; however, results suggest that cyanobacteria, particularly Microcystis, benefit from hot summers. In contrast, diatoms appear less responsive to temperature, although they tend to contribute more in colder years, with distinct shifts in species composition observed between hot and cold springs. Model simulations indicate that a 1.5 °C increase in air temperature would, via elevated water temperatures, raise average monthly phytoplankton biomass by 4% in July and by 9% in August, further promoting cyanobacteria growth.

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

The authors would like to make the following correction to the published paper [...]

The navigation waterways to the harbors of Rostock (Warnow Estuary), Germany, and Szczecin (Oder/Szczecin Lagoon), Poland, were recently deepened. Both activities required Environmental Impact Assessments. We conducted expert- and data-based ecosystem service assessments for both case studies. Additionally, we performed 3D-ecosystem model simulations. For the Oder Lagoon, the model results show that the waterway deepening increased the burial in sediments by 807 t N/a, 112 t P/a and 4661 T C/a. However, altogether, the impacts of the deepening to 12.5 m draught on the lagoon ecosystem are minor and a model application is not necessary, but the results improve the data basis for ecosystem service assessments. Our expert-based ecosystem service approach is adaptable to the needs of coastal engineering and hydraulic projects and is both easy and quick to apply and transferable. The assessment results highlight the relevance of cultural services and can complement EIAs. Our approach can especially support the early scoping stage of an EIA. It has the potential to enhance cooperation and communication with and between stakeholders, reduce conflicts, and save time. Additionally, it could improve the compilation and addressing of stakeholder concerns, potentially reducing costs associated with unnecessary studies.

The ecological importance of macrophytes is well known and reflected in nature protection law, for example, as a key biological quality element. However, the socio-economic role, such as the impact of macrophyte presence on recreational activities, is often overlooked. The purpose of this study was to assess the human benefits (or ecosystem services) provided by macrophytes. We developed a list of 25 macrophyte ecosystem services and 79 assessment indicators based on expert knowledge and literature data. First, hypothetical scenarios of coastal lagoons were developed to assess the impact of different ecological states (i.e., macrophyte coverage) and management measures (i.e., fisheries) on the ecosystem service provision. Scenario assessments were carried out by stakeholder workshops and literature search. Second, the ecosystem service potential of submerged and emergent macrophyte habitats were assessed by macrophyte experts and literature data. Results showed that cultural services are most important in terms of the overall actual provision of ecosystem services (scenario assessment) but also showing highest potential of the hypothetical ecosystem service provision (habitat assessment). Highest overall potential is shown for reeds and tall forb communities (83 out of maximum 125), followed by seagrass beds (71) and seaweed communities (61). Our ecosystem service assessment approaches (i.e., scenario and habitat-based) using socio-cultural data (i.e., stakeholders and experts-based) and biophysical data (i.e., indicators-based) can serve as supportive tools for coastal management and policy implementation visualizing the benefits of macrophytes to humans.

Every year, harbor and sailing festivals attract close to 20 million visitors in the Baltic Sea region, but their consequences on marine litter pollution are still unknown. We combine field studies with model simulations and literature reviews to quantify the annual emissions of floating macro-litter and to assess its retention in estuaries and role in Baltic Sea pollution. Results focusing on Hanse Sail in Rostock and Kiel Week are extrapolated to the entire Baltic Sea region. After the Hanse Sail 2018, the harbor pollution amounted to about 950 floating macro-litter particles/km²; 85–90% were plastics. We calculated an emission between 0.24 and 3 particles per 1000 visitors, depending on the year and the waste management system. About 0.02% of all waste generated during a festival ends up in the harbor water. The Hanse Sails contributes less than 1% to the total annual macro-litter emissions in the Warnow estuary. Model simulations indicate that over 99% of the emitted litter is trapped in the estuary. Therefore, Hanse Sails are not relevant to Baltic Sea pollution. The extrapolated Baltic-Sea-wide annual emissions are between 4466 and (more likely) 55,830 macro-litter particles. The over-30 harbor and sailing festivals contribute an estimated <0.05% to the total annual macro-litter emissions in the Baltic Sea region.

We assess the ecosystem services across the entire Baltic Sea using ecosystem model simulations and historical socio-economic data. Our approach covers 150 years, aggregated for the years around 1880, 1960, and 2010. The ecosystem services assessed include commercially usable wild fish biomass and wild plant biomass, water quality regulation (nitrogen and phosphorus retention), carbon storage, biodiversity and habitats, as well as active recreation and landscape aesthetics. In 2010, the commercially usable fish biomass in the entire Baltic Sea was 9.24 million tons. The total retention of nitrogen in the Baltic Sea was 884,135 t/a, phosphorus retention was 32,058 t/a, and carbon storage was 3,668,100 t/a. Between 1880 and 2010, the Baltic Sea-wide average biodiversity index decreased from 73 to 60, the active recreational quality index decreased from 76 to 69, and the observational recreation index declined from 91 to 78. In 2010, the most monetarily significant single ecosystem service in the Baltic Sea was nitrogen retention with EUR 26,822 million/a, followed by cultural ecosystem services. Other relevant services were fish catches (EUR 277 million/a), phosphorus retention (EUR 3854 million/a), and carbon storage (202 million/a). The latter recently showed a steep increase due to rising prices for CO2 certificates.

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.