Systematic-based approach to marine litter prevention in coastal environment: lessons and successes from the PROMAR project implementation in Guyana

Marine litter remains a persistent environmental challenge in Caribbean coastal environments, where land-based plastic waste constitutes the dominant source of debris entering marine systems. This study evaluates the implementation of the Prevention of Marine Litter in the Caribbean Sea (PROMAR) project along the Guyana coast, applying a systematic, prevention-oriented framework grounded in circular economy principles. A mixed-methods approach was adopted across four flood-prone coastal communities, integrating household material flow analysis, knowledge-attitudes-practices surveys, drainage-level waste interception, beach litter assessments, and participatory stakeholder engagement. Results indicate that packaging plastics, particularly polyethylene terephthalate and high-density polyethylene, dominate intercepted and shoreline waste, confirming strong linkages between household disposal practices, drainage networks, and marine pollution pathways. Community waste-to-value hubs, incentive-based recovery schemes, and source-proximal interception measures collectively contributed to observable reductions in plastic leakage while improving awareness, participation, and local ownership of waste management practices. The findings demonstrate that technical interventions are most effective when reinforced by education, behavioral incentives, and multi-actor governance arrangements. Policy-relevant insights highlight the importance of Extended Producer Responsibility and decentralized recovery systems for sustaining and scaling marine litter prevention. The study provides transferable evidence that systematically designed, community-anchored circular interventions can deliver socially inclusive and environmentally effective solutions in vulnerable coastal settings.

Marine litter, dominated by plastics from land-based sources, has emerged as one of the most pervasive and persistent environmental challenges affecting coastal and marine environments globally (Galgani et al., 2015; Werner and O'Brien, 2017; Jambeck et al., 2018; Napper and Thompson, 2020). An estimated 80–85% of marine litter originates from terrestrial activities, with mismanaged municipal solid waste, inadequate collection systems, urban runoff, and riverine transport acting as the principal pathways through which plastics enter the ocean (Galgani et al., 2015; Veiga et al., 2016; Chassignet et al., 2021). Guyana is an example of the acute vulnerability of continental Caribbean states to marine litter pollution (Diez et al., 2019; Graham, 2024). Approximately 90% of the country's population, economic activities, and critical infrastructure are concentrated along a narrow, low-lying coastal plain that lies largely below mean sea level and is protected by an extensive but aging system of sea defenses and drainage canals (Hickey and Weis, 2012; Bassett and Scruggs, 2013; Vaughn, 2022; Oyedotun et al., 2025). In this context, ineffective solid waste management directly translates into coastal and marine pollution, as improperly disposed plastics are readily mobilized by rainfall, tides, and flood events into canals, rivers, and eventually the Atlantic Ocean. Empirical studies along Guyana's coast have shown that plastics account for nearly half of all recorded beach litter items, with no surveyed sites achieving high cleanliness grades (Oyedotun and Johnson-Bhola, 2019). These findings underscore the structural nature of the problem, linking marine litter not only to environmental degradation but also to urban flooding, public health risks, and climate vulnerability (Oyedotun et al., 2021).

In Small Island Developing States (SIDS) and low-lying coastal countries, these pressures are intensified by rapid coastal urbanization, limited waste management infrastructure, and high dependence on healthy coastal and marine ecosystems for livelihoods, food security, and tourism (Hewawasam, 2002; Islam and Tamanna, 2022; Graham, 2024; Leal Filho et al., 2025). The Caribbean region is recognized as one of the global hotspots for marine litter accumulation (Bennett-Martin et al., 2016; Oyedotun and Johnson-Bhola, 2019; Xu et al., 2024; Hamer and Oyedotun, 2026). High population densities along the coast, extensive use of single-use plastic packaging, and fragmented waste governance systems have resulted in significant volumes of plastic leakage into nearshore waters and beaches (Bennett-Martin et al., 2016; Hamer and Oyedotun, 2026). Regional assessments consistently report shoreline litter densities exceeding global averages, with plastics—particularly polyethylene terephthalate (PET), high-density polyethylene (HDPE), and mixed packaging materials—constituting the dominant fraction of debris (Maddalene, 2024; Graham, 2024; Leal Filho et al., 2025). Beyond their ecological impacts, plastics impose substantial socio-economic costs by degrading fisheries, increasing flood risks through clogged drainage networks, undermining tourism revenues, and posing long-term risks to human health through microplastic exposure and associated chemical contaminants (Danso, 2024).

From a global policy perspective, marine litter has increasingly been framed as a systemic failure of linear production and consumption models (Newman et al., 2015; Mæland and Staupe-Delgado, 2020). Conventional “take-make-dispose” systems externalize environmental costs and overwhelm downstream waste management capacities, particularly in developing coastal states (Elisha, 2020). In response, the circular economy paradigm has gained prominence as a transformative framework for addressing plastic pollution (Montocchio et al., 2025). By prioritizing waste prevention, material recovery, reuse, and recycling, circular economy approaches seek to retain material value within the economy while minimizing leakage into the environment. Importantly, the effectiveness of circular solutions depends not only on technical interventions but also on governance reforms, market incentives, and sustained community engagement (Iacovidou et al., 2021; Dagiliene et al., 2021).

Within the Caribbean, regional and international initiatives have begun to operationalise circular economy principles to combat marine litter (Graham, 2024). Among the most comprehensive of these efforts is the Prevention of Marine Litter in the Caribbean Sea (PROMAR) project, funded by the German Federal Ministry for the Environment, Climate Action, Nature Conservation and Nuclear Safety and implemented by adelphi in partnership with the United Nations Environment Programme's Cartagena Convention Secretariat. PROMAR adopts a multi-country, multi-actor approach, combining data-driven monitoring, pilot circular economy interventions, institutional capacity building, and public awareness to reduce plastic flows from land-based sources into the Caribbean Sea.

The PROMAR project is distinctive in its emphasis on demonstration sites, where interventions are designed to be locally grounded yet scalable across national and regional contexts. By integrating material flow analysis, community-based monitoring, waste interception technologies, and incentive-based recovery schemes, PROMAR seeks to move beyond episodic clean-ups toward systemic prevention of marine litter. Equally significant is the project's alignment with emerging policy instruments, particularly Extended Producer Responsibility (EPR), which shifts part of the financial and operational burden of plastic waste management upstream to producers and importers.

In Guyana, PROMAR is implemented through a partnership led by the University of Guyana Faculty of Earth and Environmental Sciences, focusing on densely populated and flood-prone communities along the East Coast Demerara corridor. These communities, characterized by extensive drainage networks that discharge directly into coastal waters, represent critical intervention points to prevent plastic leakage. The Guyana pilot integrates baseline surveys, material flow analysis, citizen-science monitoring, and physical waste interception with community-level waste-to-value initiatives, including decentralized recycling hubs and incentive-based collection schemes. Education, youth engagement, and behavioral change communication form another core component of the intervention, recognizing that sustainable waste management outcomes depend on long-term shifts in knowledge, attitudes, and practices.

Despite growing recognition of circular economy solutions in policy discourse, empirical evidence documenting how integrated, community-based systems function in practice—particularly in low-income coastal contexts—remains limited. Many marine litter initiatives report outputs (e.g., tons collected) but provide insufficient analysis of the systemic conditions, governance arrangements, and social dynamics that enable sustained prevention. There is, therefore, a critical need for implementation-focused studies that examine not only what works, but why and under what conditions.

The current paper presents a mechanistic explanation, grounded in theoretical foundations, of marine litter prevention through the implementation of the PROMAR project in Guyana. The paper highlights the planning and implementation process of integrated interventions within the circular economy concept, analyses the results of these interventions regarding reductions in plastic leakage using quantitative mass-balance and statistical approaches, and derives valuable insights relevant to policymakers and practitioners. In this way, the study attempts to contribute to existing knowledge on marine litter prevention mechanisms from the perspective of circular economy implementation.

Study design and conceptual framework

This study adopts a mixed-methods, systems-based implementation research design to evaluate marine litter prevention through circular economy interventions under the PROMAR project in Guyana. The methodological framework is grounded in the source-pathway-receptor model for marine litter, combined with circular economy principles that prioritize prevention, interception, recovery, and reintegration of plastic materials into productive use. The approach integrates quantitative waste flow measurements with qualitative social and institutional assessments, enabling an evaluation of both biophysical outcomes (plastic leakage reduction) and enabling conditions (behavioral change, stakeholder engagement, and governance relevance).

The methodology was implemented sequentially across four phases (Figure 1): (i) baseline assessment and diagnostics, (ii) intervention design and deployment, (iii) monitoring and evaluation, and (iv) synthesis of lessons and policy-relevant insights. This structure ensured that interventions were evidence-based, adaptive to local contexts, and aligned with PROMAR's regional monitoring and reporting requirements.

Study area and site selection

The Guyana PROMAR pilot was implemented along the East Coast Demerara, targeting the communities of Mon Repos, De Endragt, Good Hope, and Lusignan (Figure 2). These sites were selected using a multi-criteria approach that considered population density, proximity to drainage canals and coastal outfalls, historical flooding incidence, observed litter accumulation, and local institutional readiness. The study area is characterized by an extensive network of canals and sluices that discharge directly into nearshore marine waters, making these communities critical control points for land-based plastic leakage.

Each community represents a typical coastal settlement within Guyana's low-lying coastal plain, where household waste management practices, informal dumping, and seasonal flooding interact to exacerbate marine litter transport. The spatial configuration of the sites allowed for comparative analysis across communities while maintaining consistency in environmental and socio-economic conditions.

Baseline surveys and material flow analysis

Household material flow analysis (MFA) surveys and knowledge-attitudes-practices (KAP) assessment

Baseline data on plastic consumption, disposal behavior, and environmental awareness were collected through structured household surveys and KAP questionnaires. A total of 417 households were selected randomly from four villages using stratified sampling to represent diversity in age, income, and dwelling types as part of the household material flow analysis (MFA). Stratification involved following the enumeration districts in the 2022 Guyana Population and Housing Census and applying Proportional Allocation based on community sizes. The MFA was based on standard UNEP KAP guidelines for marine debris survey design (United Nations Environment Programme, 2020) and validated through expert panel review (N=5 environmental sociologists) and pilot testing (N = 30 respondents in a non-study village). Internal consistency of measurement was verified via Cronbach's α, which resulted in an α = 0.82, α = 0.78, and α = 0.85 reliability coefficient for knowledge, attitudes, and practice scales, respectively. Given an estimated total of 12,400 households in the study area, the resulting n = 417 sample size yields a 95% confidence level and a margin of error of ±4.8% (Cochran, 1977). The MFA survey instrument captured information on plastic use patterns, disposal pathways, awareness of marine litter impacts, willingness to participate in recycling schemes, and perceived barriers to proper waste management.

The development of the questionnaire involved the following steps: (i) modification according to the UNEP KAP guidelines; (ii) expert assessment in terms of content validity (CVI = 0.89); and (iii) testing in terms of comprehensibility and time needed for completion. Test-retest reliability was assessed among the sub-sample (n = 30) 2 weeks apart, with results yielding an ICC > 0.75 on all scales.

In parallel, additional KAP data were collected from approximately 500 community members through youth-led citizen science activities, facilitated in collaboration with the Caribbean Youth Environment Network (CYEN). These data provided insights into generational differences in attitudes and informed the design of targeted education and incentive mechanisms.

Material flow analysis (MFA)

The Mass-Balance Analysis was utilized as a diagnostic tool to follow the flows of plastics from households to various disposal channels and environmental leaks, applying the standard mass balance concept (Brunner and Rechberger, 2016). Specifically, the mass balance concept can be stated as follows:

Here, M input refers to household plastic consumption, measured using the survey-based estimation of purchase frequency and standard plastic package weights. M recovery reflects household-generated plastics sent to formal or community recycling centers, whereas M leakage stands for the amount of plastics that enter drainage systems or coastal areas, estimated by measuring booms and shoreline debris. M accumulation reflects the amount of plastic waste that remains within households, burns or is disposed of via informal channels. The symbol ± ε allows for measurement errors in reported behavioral data and partial geographic monitoring coverage.

Instead of serving as an arithmetic calculation tool, the mass balance structure facilitated the collection of flow-rate indicators and the comparative analysis of the most prevalent pathways of household plastic waste. Survey data helped estimate the baseline levels of plastic input and disposal practices, which were further verified using municipal garbage collection statistics (GoG, 2013) and on-the-ground monitoring findings to identify potential leakage points. Normalization measures considered average per-capita consumption rates and drainage-basin features for inter-community comparisons. Using this approach, MFA demonstrated a relationship between household consumption and disposal behavior and the accumulation of plastic in water bodies.

Monitoring of plastic leakage and waste interception

River and canal boom installation

The floating waste booms were constructed using locally sourced, low-cost materials consisting of 40 mm polypropylene rope and HDPE shrimp netting (500 μm mesh size, 2.5 cm). In total, three demonstration sites were installed at three major drainage catchments, Mon Repos/Good Hope, Triumph, and Annandale/Lusignan (Figure 3). The booms extended 8–12 meters across the canal width and were oriented at a 45° angle to the flow direction to reduce hydraulic drag and increase surface coverage (modified after Parker-Jurd et al., 2022). The booms were anchored with shackle bolts to accommodate variations in water levels. The booms were checked daily for maintenance and waste collection during heavy rains. Waste collected was sorted on-site according to the CEGESTI and Abrelpe classification systems, weighed to within 0.1g using precision electronic scales, and recorded.

Beach litter surveys

Independent surveys to assess the presence of beach litter were conducted in accordance with the Methodological Guide for Conducting Solid Waste Sampling on Beaches (CEGESTI and Abrelpe, 2022). Three transects with a width of 10 m were demarcated perpendicular to the shore on Unity Beach, Kingston Beach and No. 63 Beach (See Figure 3) from the berm to the low water mark, with one transect in an area with a high litter abundance, medium litter abundance, and low litter abundance. Each item greater than 2.5 cm in size was noted and classified in line with the (CEGESTI and Abrelpe 2022), weighed to the nearest 0.1 gram, and physically collected to avoid counting the same litter item twice.

Litter categorization was done by (i) material category: plastics associated with fishing, Plastics associated with daily consumption, metal, fabric, and others; and (ii) product types: beverage bottles and containers, food containers and wrappers, plastic bags and films, fishing equipment, household goods, and unidentified fragments. Such an approach enabled correlation between the materials' composition and their intended use, providing a basis for intervention measures targeting specific sources. These data provided an independent measure of coastal litter composition and served as a reference point for evaluating changes in plastic leakage over time.

Circular economy interventions

Community waste-to-value hubs

Four decentralized waste-to-value hubs were established—one in each community—to facilitate source separation, temporary storage, and aggregation of recyclable plastics. The hubs were designed to be accessible, low-cost, and community-managed, with clear signage and sorting guidelines. Collected materials were periodically transferred to the University of Guyana's Circular Economy Innovation Lab for closed-loop processing.

Incentive-based waste-for-token exchange scheme

An incentive mechanism was piloted to encourage participation in plastic recovery. Residents in the controlled environment, schools within the communities, are able to exchange sorted plastics for non-cash rewards, including school supplies or household items. Transaction records are being maintained to track participation rates, material quantities, and incentive uptake. This mechanism is being evaluated as a behavioral intervention aimed at reinforcing consistent waste separation and collection practices.

Recycling and processing partnerships

Recovered plastics were processed in the University of Guyana Faculty of Earth and Environmental Sciences (UG-FEES) Lab, which provided shredding, cleaning, and recycling services where technically feasible. Residual materials unsuitable for recycling were managed in accordance with national waste regulations.

Education, training, and community engagement

Education and awareness activities were integrated throughout the project lifecycle. Workshops, school programmes, fairs, and community meetings were conducted to disseminate information on marine litter impacts, circular economy principles, and practical waste management skills. Targeted training sessions focused on youth groups, women's associations, and local artisans, with an emphasis on reuse, upcycling, and eco-entrepreneurship.

Qualitative feedback was collected through focus group discussions and stakeholder meetings to assess perceptions of the interventions, identify implementation challenges, and capture community-driven recommendations for improvement.

Monitoring, evaluation, and data analysis

Project performance was assessed using a set of quantitative and qualitative indicators aligned with PROMAR's regional monitoring framework (PROMAR Monitoring Tools). Key indicators included: Volume and composition of plastics intercepted by booms; Quantity of plastics collected through community hubs; Changes in KAP survey responses over time, among others.

All statistical analyses were performed using R version 4.3.1. Normality of continuous variables was assessed using the Shapiro-Wilk test, and nonparametric tests were used when assumptions were not met. Cross-site variations in boom interceptions and beach litter density were compared with the Kruskal-Wallis H test, followed by Dunn's multiple comparisons with adjustments (α = 0.05). Seasonality of intercepting volumes per month was estimated using the Mann-Kendall trend test. The correlations between monthly rainfall (mm; obtained from the Guyana Hydrometeorological Service) and mass of plastic intercepted were calculated using Spearman's rank correlation coefficient (ρ). The efficiency of the booms was calculated using E = W_intercepted / (L_channel × T_days) (kg·m −1 ·day −1), where L_channel is the width of the channel where the booms were deployed. Comparisons of beach litter density before and after deployments were made using the paired Wilcoxon signed-rank test. Associations between knowledge, attitudes, and practices (KAP) scores and hub membership rate were determined using the point-biserial correlation coefficient.

Ethical considerations and limitations

Participation in surveys and community activities was voluntary, and informed consent was obtained from all respondents. Data were anonymised to protect participant confidentiality. While the study provides robust implementation-level insights, limitations include the relatively short monitoring period and reliance on self-reported behavioral data. These constraints are acknowledged in the interpretation of results and the discussion of scalability.

However, the methodology utilized in this study and project provides a replicable and context-sensitive framework for evaluating community-based circular economy interventions aimed at marine litter prevention in vulnerable coastal environments.

Analytical framework and theoretical positioning

The findings of this empirical research can be placed into three related theoretical fields: (i) the theory on the implementation of the circular economy, according to which the development of technology, behavior and institutions is required for achieving a system-wide transition (Geissdoerfer et al., 2017; Kirchherr et al., 2017); (ii) behavioral economics nudges, according to which non-monetary incentives and visible infrastructure act as choice-architecture tools in fostering environmentally-friendly behavior (Thaler and Sunstein, 2008); and (iii) polycentric governance, which holds that for the effective management of environment in the absence of data, it is essential to coordinate actions on various levels from local to state levels (Ostrom, 2010).

Snapshots Guyana-PROMAR completed activities

This section presents a synthesis of the key successes of the PROMAR Implementation Project in Guyana, organized around the four core activities illustrated in Figure 4. Drawing on project implementation evidence and progress reports, the analysis demonstrates how PROMAR effectively operationalised a source-to-sea approach through material flow analysis, circular economy piloting, capacity building and policy dialogue, and stakeholder awareness and dissemination. Collectively, these activities contributed to strengthening data availability, institutional capacity, policy coherence, and public engagement for marine litter prevention in Guyana. By situating project outcomes within relevant international literature, this section highlights PROMAR's contribution to advancing best practices in marine litter governance, particularly in the context of Small Island and coastal developing states.

Activity 1: material flow analyses and establishment of monitoring mechanisms

The PROMAR Implementation Project in Guyana achieved a major milestone through the systematic application of Material Flow Analysis (MFA) to quantify plastic leakage from terrestrial sources into aquatic and coastal environments. MFA is widely recognized as a robust analytical framework for tracing waste generation, transport pathways, and environmental leakage, particularly in data-scarce developing contexts (Brunner and Rechberger, 2016; United Nations Environment Programme, 2020). Through the installation of in-stream litter traps, river booms, shoreline litter surveys, and household-level waste audits, Guyana-PROMAR generated the first empirically grounded baseline of marine litter flows for selected coastal communities in Guyana. The interception of tens of thousands of kilograms of plastic waste over successive monitoring periods provided direct, measurable evidence of land-based pollution sources, addressing a critical data gap previously noted for Caribbean coastal states [United Nations Environment Programme (UNEP), Caribbean Environment Programme (CEP), 2019].

Beyond data acquisition, Activity 1 successfully proposed the institutionalization of marine litter monitoring within national and sub-national governance structures. Monitoring protocols were developed in alignment with UNEP methodological guidance and anchored within the operational workflows of key public authorities, including the Environmental Protection Agency and drainage management institutions. The integration of behavioral surveys alongside physical waste measurements reflects best practice in source-to-sea approaches, which emphasize the linkage between human behavior, waste systems, and environmental outcomes (Jambeck et al., 2015; Borrelle et al., 2020). Collectively, these achievements established a scientifically credible and policy-relevant monitoring system capable of supporting long-term assessment, adaptive management, and evidence-based decision-making for marine litter prevention in Guyana.

Activity 2: circular economy pilot implementation

Under Activity 2, PROMAR effectively translated diagnostic evidence into solution-oriented circular economy interventions tailored to Guyana's socio-economic and institutional context. Circular economy principles—centered on waste reduction, material recovery, and value retention—are increasingly recognized as critical to mitigating marine plastic pollution, particularly in Small Island and coastal developing states (Organisation for Economic Co-operation and Development, 2016, 2022; Ellen MacArthur Foundation, 2017). Through household Knowledge-Attitudes-Practices (KAP) surveys and structured stakeholder consultations, the project identified behavioral, infrastructural, and market barriers to circularity while also documenting local opportunities for waste valorisation. The completion of consultation reports and an academic review of circular economy approaches provided both empirical grounding and conceptual clarity for subsequent pilot design.

A significant achievement of Activity 2 was the development of the Coastal Waste-to-Value Initiative, which operationalised circular economy theory into a context-specific pilot framework. By engaging in exploring partnerships for recycling and waste-to-product schemes, Guyana-PROMAR aligned with emerging evidence that public-private collaboration is essential for scaling circular solutions in developing economies (Lacy et al., 2020). The conceptualization of the “Guyana Circle—The Circular Economy Lab” further positioned the University of Guyana as a national innovation hub, strengthening the research-policy-practice nexus. These outcomes demonstrate Guyana-PROMAR's contribution to moving beyond waste characterization toward actionable interventions capable of delivering measurable reductions in plastic leakage.

Activity 3: capacity building and trans-national policy dialogue

Guyana-PROMAR's achievements under Activity 3 significantly strengthened Guyana's institutional and policy capacity to address marine litter and plastic waste management. The development of a national policy brief on marine litter prevention and Extended Producer Responsibility (EPR) reflects internationally endorsed policy instruments for reducing plastic pollution at source [United Nations Environment Programme (UNEP), Caribbean Environment Programme (CEP), 2019; Organisation for Economic Co-operation and Development, 2016, 2022]. By contributing technical inputs to the review of Guyana's Solid Waste Management Bill, the project ensured that global best practices were contextualized within national legislative processes, enhancing policy coherence and regulatory effectiveness. The successful convening of a National Dialogue on Marine Litter Prevention further facilitated cross-sectoral consensus, a factor widely recognized as essential for effective environmental governance (Boas et al., 2016).

At the regional and international levels, PROMAR advanced transnational learning and knowledge exchange through active participation in Caribbean and global fora, including PROMAR Summits, regional study visits, and international coastal resilience conferences. Such engagement aligns with literature emphasizing the importance of regional cooperation and policy harmonization in addressing transboundary marine pollution (Vince and Hardesty, 2018). Capacity-building workshops on EPR and circular economy business models equipped policymakers and practitioners with practical tools to replicate and scale pilot interventions beyond demonstration sites. These achievements collectively positioned Guyana as both a beneficiary and contributor within regional marine litter governance frameworks.

Activity 4: stakeholder awareness and dissemination

Activity 4 delivered substantial progress in enhancing stakeholder awareness and promoting behavioral change, a critical yet often under-resourced component of marine litter interventions (Hartley et al., 2015). The completion of large-scale KAP surveys provided empirical insight into public perceptions and behaviors related to plastic consumption and disposal, enabling the design of targeted communication strategies. Awareness campaigns—including coastal clean-ups, public exhibitions, and community-based activities—translated abstract pollution concepts into tangible local experiences, reinforcing evidence that participatory engagement strengthens environmental stewardship (Schultz, 2014).

Equally significant was Guyana-PROMAR's investment in education and knowledge dissemination through schools and mass media. The development and deployment of a Marine Litter School Engagement Curriculum aligns with research demonstrating that early environmental education fosters long-term pro-environmental behavior (Stevenson et al., 2017). Strategic radio and television outreach, complemented by documentary production, expanded the project's reach beyond immediate pilot communities, embedding marine litter prevention within national public discourse. Collectively, these achievements ensured that Guyana-PROMAR's impacts extended from technical monitoring and policy reform to societal awareness and behavioral transformation, thereby reinforcing the sustainability of project outcomes.

Baseline conditions and scale of marine litter in Guyana

Baseline assessments conducted under the PROMAR Guyana pilot confirm that marine litter represents a severe and systemic challenge along the country's low-lying coastal zone. Guyana is ranked among the top ten countries globally for per-capita mismanaged plastic waste entering the ocean, with an estimated leakage rate of approximately 1.59 kg per person per year (Diez et al., 2019). This figure reflects structural weaknesses in solid waste collection, limited recycling capacity, and the concentration of population and economic activities along the coast.

The Unity Beach survey conducted in the context of the project created the initial standardized baseline data on marine litter, in relation to the implementation of the PROMAR Project in Guyana. 26.2 kg of debris were collected in total during the survey in an area of 830 m 2. Plastics associated with consumption constituted the major share in terms of the composition of the litter (42.02% of the total number of items, 279 items), with common examples being food wrappers, single-use containers, and bottle caps, suggesting that single-use plastic items are a major source of marine pollution (see Figure 5). It is important to highlight the difference between the share of different plastics in terms of mass out of the total debris mass, with hard plastic particles accounting for 4,070 g, which constitutes 15.54% of the total mass, even though there are only 42 such particles (see Figure 5).

Similarly, among other identifications, the baseline survey identified potential public health and safety risks associated with marine litter. Notably, 1,095 g of disposable diapers and 2,005 g of glass were recorded, indicating inadequate waste disposal practices and lapses in safety management. These findings underscore the need for improved waste handling protocols in coastal areas.

Earlier surveys done before the introduction of PROMAR have shown that plastics represent approximately 48–50% (PROMAR Survey = 63% (includes plastics from fishing, consumption, everyday use and particulate)) of total debris items found on the shorelines of Guyana with PET bottles, food packaging, fragments, and disposable consumer products being the most common types (Oyedotun and Johnson-Bhola, 2019). These types of marine debris composition correspond with those reported by other Caribbean assessments, showing that plastics consistently represent the largest portion of litter on shores across the region. Concurrently, monitoring reports show litter densities of up to 2,000 to 3,900 items/km that are well above global averages (Ambrose and Walker, 2023). While these two measurements should not be combined, the combination of evidence confirms that marine pollution in Guyana is serious and driven primarily by plastics. Initial monitoring findings indicate that litter leakage is predominantly terrestrial and related to drainage channels and flooding dynamics. Alongside the evidence gathered in the field, the results of the Household Material Flow Analysis (MFA) show that surveyed households tend to rely extensively on single-use and refillable plastic packaging (Figure 6). It was reported that 76.74% of the respondents regularly use plastic water jugs for 19 liters (5 gallons) per week, and 46.52% consume four or more plastic bottles of beverages per week. Other forms of plastic consumption are represented by cooking oil containers (51.56%), snack packaging (40.00%) and disposable cups (35.01%). Nonetheless, waste management among households still remains inefficient: 42.21% of respondents do not practice any waste separation, only 6.71% use a professional garbage collection service, 11.99% regularly dump garbage, and 10.55% burn waste on a weekly basis.

These environmentally unsustainable practices point to systemic inadequacies in municipal waste management services. Although 50.36% of households reported having access to waste collection, many indicated that existing services are insufficient and require strengthening. There was strong support for improved waste management interventions, with 60.19% of respondents favoring expanded waste collection services, 52.52% advocating for the provision of additional public waste bins, and 31.00% identifying free recycling facilities as a significant incentive for improved waste handling. These findings provide an empirical basis for targeted infrastructure upgrades and the development of public-private or community partnerships to support refill stations and reusable container systems.

Quantification of plastic leakage and waste interception

The use of floating waste-interception booms in the drainage canals of Mon Repos, De Endragt, Good Hope, and Lusignan enabled the collection of accurate data on the leakage of plastic pollution from land to water environments. The preliminary data reveal that plastic waste consistently collects in the interception points. Among the 59,466 kg of plastics intercepted, which accounted for 52.4% of the total waste collected, the most abundant material types were PET bottles (13.5%), HDPE containers (16%), plastic bags and films (31.5%), and mixed packaging materials (39%). This type of material is consistent with the household MFA data.

Interception efficiency across different sites showed a significant heterogeneity (Kruskal-Wallis H(3) = 18.7, p < 0.001, η 2 = 0.31) with Mon Repos/Good Hope being the most productive site with respect to mean monthly interception capacity (4,821 ± 1,205 kg) due to the proximity to the point where two large drainage channels converge. The temporal pattern analysis suggested a significant positive Mann-Kendall trend (τ = 0.68, p = 0.003) in the case of total monthly interception amount caused by changing precipitation patterns throughout the year. In addition, Spearman correlation analysis yielded a strong positive relationship between the amount of precipitation and plastic interception (ρ = 0.71, p < 0.01).

One of the preliminary principal environmental achievements of Guyana-PROMAR Activity 1 was the large-scale interception and removal of solid waste from inland waterways. Under PROMAR Output 1, a total of 113,399 kg (113.4 tons) of waste was collected between March and November 2025 from three in-stream trap locations. Plastics constituted 59,466 kg, representing 52.4% of the total collected material. This interception directly prevents land-based waste from being transported into the Atlantic Ocean. The Mon Repos/Good Hope site, located at a major drainage junction serviced by a pumping system, accounted for the highest recovery, intercepting 94,432 kg of waste. Notably, during a single high-rainfall event in June 2025, this site alone captured 26,540 kg of debris (Figure 7).

The results demonstrate that low-cost, adapted floating trap systems can be highly effective in intercepting marine litter in drainage networks. In several instances, these simple boom-trap prototypes outperformed more expensive mechanical collection systems, which have also been reported to pose risks to aquatic fauna (Parker-Jurd et al., 2022). Constructed from locally available materials such as rope, shrimp netting, bamboo, and elastic anchors, the traps are easily deployed, maintained, and managed by community groups or Neighborhood Democratic Councils (NDCs), indicating strong potential for long-term sustainability. In addition to functioning as physical pollution barriers, the floating traps serve as real-time monitoring platforms, enabling the systematic collection of data on waste volumes, material composition, and seasonal variability in debris flows.

Efficiency in boom use, measured in kilograms intercepted per meter of canal width per day, varied between 1.8 kg m −2 day −2 and 4.3 kg m −2 day −2. The highest efficiency correlated with discharge peaks in June and November, which emphasizes the importance of scheduling maintenance according to hydrological patterns. In the case of litter density in the area surrounding Unity Beach, a significant decrease was observed after the installation of the hub (median before: 0.42 item/m 2; median after: 0.28 item/m 2; W = 18; p = 0.024; r = 0.52).

Although full annualized interception data are still being consolidated, early trends indicate a measurable reduction in visible plastic debris downstream of interception points, supporting the effectiveness of source-proximal waste capture as a preventive strategy.

Performance of community waste-to-value interventions

The establishment of four decentralized waste-to-value hubs increased the willingness of residents to participate in sorting of recyclable plastics at the community level. Participation records indicate steady engagement across all four pilot communities, with regular delivery of sorted PET and HDPE materials to collection hubs. The Coastal Waste-to-Value Initiative implemented under the Guyana-PROMAR programme demonstrates how integrated, community-centered circular economy interventions can translate waste management challenges into measurable environmental, social, and economic outcomes. As illustrated in Figure 7, the initiative combines decentralized collection systems, incentive mechanisms, small-scale recycling technologies, and awareness-raising into a closed-loop operational model. Consistent with circular economy theory, the results indicate that system-level integration—rather than isolated technical solutions—is a critical determinant of performance in community waste-to-value interventions (Geissdoerfer et al., 2017; Kirchherr et al., 2017).

Component 1 of the initiative (Figure 7) focused on community-based plastic collection using specially designed bins supported by clear visual sorting instructions. The results indicate improved compliance with source-level segregation, particularly for PET, HDPE, and LDPE plastics. Previous studies have shown that visible, easy-to-understand guidance at the point of disposal significantly improves sorting behavior, especially in low- and middle-income contexts where formal recycling systems are limited (Bernstad, 2014). In this pilot, the bins functioned not only as collection infrastructure but also as behavioral nudges, reinforcing daily waste-sorting practices.

The strategic placement of collection hubs within highly visible community spaces further enhanced participation by pupils in schools and youth groups. This finding aligns with evidence that decentralized and locally accessible waste infrastructure increases participation rates and reduces improper disposal, particularly in coastal settlements where drainage systems are highly sensitive to solid waste accumulation (Jambeck et al., 2015; United Nations Environment Programme, 2018). In flood-prone environments such as Guyana's East Coast, these improvements are especially relevant for reducing plastic leakage into waterways.

Component 2, the waste-for-token exchange scheme, emerged as a key driver of sustained engagement. By assigning tangible value to sorted plastic waste, the initiative addressed a widely documented barrier to community recycling: the lack of immediate incentives for participation (Ferrara and Missios, 2005; Kaza et al., 2018). Although modest in monetary terms, the token system reinforced regular return behavior and strengthened community ownership of the intervention. From a performance perspective, the incentive mechanism contributed to stabilizing material flows into the processing stage, reducing fluctuations commonly observed in voluntary recycling schemes. The decision to link rewards to locally produced goods rather than cash further enhanced circularity and local economic circulation, consistent with findings that non-cash, community-linked incentives (in our case, school materials and items) can be particularly effective in small-scale circular economy systems (Kaza et al., 2018).

Component 3 (Figure 7) represents the technical core of the intervention, demonstrating the feasibility of small-scale, decentralized plastic recycling using shredders, injection molds, and additive manufacturing. The results confirm that low-cost, modular recycling technologies can be effectively deployed in university-community partnerships, producing consistent outputs while remaining accessible for training and local maintenance. Similar systems have been shown to reduce barriers to entry for recycling entrepreneurship and improve resilience in resource-constrained settings (Baechler et al., 2013). The production of closed-loop souvenir items from locally collected plastics is a critical performance indicator, as it demonstrates value retention within the local system. Closed-loop recycling models are widely recognized as more resource-efficient than downcycling pathways, particularly when transport distances are minimized, and products are sold within the same socio-economic system (Ghisellini et al., 2016).

The pilot also generated early evidence of economic viability through the planned sale of recycled plastic souvenirs at university fairs, schools, and community events. While revenues remain modest at the pilot stage, the initiative illustrates how waste-to-value systems can transition from cost-centered waste management toward income-generating micro-enterprises. The core challenge of the sustainability of the incentive system lies in its ability to generate enough revenue from the recycled plastic waste to cover its costs. Currently, at the pilot level, proceeds from recyclables collection and sale of souvenirs do not generate sufficient profit to cover the cost of obtaining non-cash rewards and logistics. Still, the choice of non-cash incentives that originate from the local community significantly cuts down costs compared to the standard system involving cash. Moreover, with the growing volumes and increased sorting efficiency of plastic waste, the market price of sorted PET and HDPE is expected to increasingly compensate for the incurred costs. Following the example of similar circular economy projects in other communities, the initial phase of subsidizing the project is most likely to occur due to the lack of financial feasibility until a certain threshold is reached (Ferrara and Missios, 2005; Kaza et al., 2018). Future phases of the project will include cost-recovery analysis in order to enhance the incentive system and develop sustainable financing methods. This aligns with literature emphasizing the role of circular economy initiatives in supporting inclusive green jobs and local entrepreneurship (Douglas et al., 2008; Murray et al., 2017). Involvement of university students, youth groups, and local primary and secondary schools in production and marketing activities contributed to skills development in eco-design, machine operation, and small-business management. Such capacity-building outcomes are widely regarded as essential for the long-term sustainability of community-based environmental interventions (United Nations Development Programme, 2020).

Guyana-PROMAR Coastal Waste-to-Value Initiative (Figure 8) demonstrates strong performance as a pilot-scale intervention, with clear environmental, social, and economic co-benefits. The findings support broader evidence that community-embedded, low-tech circular economy solutions are particularly well suited to small coastal states facing marine litter and climate vulnerability (United Nations Environment Programme, 2021). Scaling the model will require expanded market access, sustained incentives, and continued institutional support; however, the results indicate that the foundational design is robust, adaptable, and transferable to other coastal contexts.

Behavioral change and community engagement outcomes

Environmental outputs and participation trends from coastal cleanup activities

The Guyana-PROMAR project's interventions demonstrate measurable early success in combining direct environmental remediation with structured public engagement on marine litter prevention. Three major coastal cleanup activities were implemented between April and September 2025, collectively engaging 173 volunteers and removing approximately 1,306.36 kg of marine debris from Guyana's shoreline environments. The initial pilot cleanup at Unity Beach mobilized 28 participants and resulted in the removal of 26.197 kg of litter across approximately 58.8 m in length and 10.0 m in width, corresponding to an estimated area of 588 m 2 of shoreline. The Kingston Seawall cleanup removed 67.54 kg through 24 volunteers covering a shoreline section approximately 804.50 m in length and 2.00 m in width, corresponding to an estimated area of 1,609.00 m 2. The largest activity, the 2025 International Coastal Cleanup (ICC) at No. 63 Beach, Corentyne, mobilized 121 volunteers and yielded 1,216 kg of collected waste across approximately 115,848.00 m 2 of coastal area (965.40 m length × 120.00 m width), reflecting a substantial scaling of outreach and environmental impact. Waste characterization across all sites revealed the dominance of plastic fragments, beverage bottles, food packaging, and single-use consumer items, reinforcing the widely documented role of land-based sources as primary contributors to coastal marine litter (See Figure 9a for an example of Kingston Seawall and Figure 9b for that of Number 63 Beach Clean-up items, respectively). This pattern aligns with global estimates that mismanaged plastic waste entering waterways constitutes the largest driver of marine debris accumulation (Jambeck et al., 2015; Lebreton et al., 2017).

Awareness, attitudinal shifts, and behavioral intent following experiential interventions

Post-activity survey findings across all cleanup events revealed consistently high levels of awareness and strong attitudinal alignment with marine litter prevention goals. Participants reported mean understanding scores ranging from 9.8 to 10.0 out of 10, including unanimous agreement that marine litter represents an urgent environmental problem requiring immediate action. Participants also expressed strong personal responsibility (mean ≈ 9.8–10.0) and a high likelihood of adopting improved daily waste practices (mean ≈ 9.4–9.6) (Table 1).

The correlation of a point biserial nature between the standardized composite scores of knowledge, attitude, and practices (KAP) and the frequency of visiting hubs on a consistent basis (≥3 times per month) was found to be significantly positive in nature (r_pb = 0.41, p < 0.01). This finding shows that improvements in knowledge and attitudes lead to behavioral involvement.

These findings reinforce evidence that experiential environmental education—particularly through direct participation in clean-ups—enhances cognitive engagement and increases pro-environmental attitudes by making ecological problems visible and personally meaningful (Ballantyne and Packer, 2009). While behavioral intent does not guarantee sustained behavioral change, it represents a critical precursor within established frameworks such as the Theory of Planned Behavior (Ajzen, 1991). Guyana-PROMAR's consistently high behavioral intention scores therefore suggest early effectiveness in influencing key psychosocial drivers of environmental action. Qualitative feedback further indicates deeper learning outcomes, with participants highlighting plastic persistence, microplastic formation, and food-chain contamination as key takeaways. Similar studies have shown that linking marine litter to human health and food security strengthens motivation for behavioral change (Hartley et al., 2018).

Community-based youth engagement and diversified awareness strategies

Beyond shoreline remediation, Guyana-PROMAR implemented diversified community engagement modalities targeting youth and the wider public. The World Environment Day Scavenger Hunt engaged 39 young participants (aged 15–30) through gamified learning and interactive environmental challenges, demonstrating the value of innovative outreach formats in sustaining youth interest. Gamification has been widely recognized as a powerful tool for strengthening motivation, peer learning, and knowledge retention in environmental education contexts (Deterding et al., 2011).

Similarly, PROMAR's participation in the EPA World Environment Day Awareness Walk and Exhibition reached over 85 individuals, exceeding engagement targets and enhancing multi-sectoral visibility (Figure 10). Such broad-based outreach reflects the importance of inclusive stakeholder platforms in strengthening marine litter governance, particularly in developing coastal states where enforcement capacity and infrastructure constraints remain significant (Vince and Hardesty, 2017).

School-based interventions and early stewardship development

Awareness programmes were delivered in schools through Guyana-PROMAR, reaching 133 students across three schools. The outcome of the program has been very positive as reflected in the self-assessed results after the session. Self-assessment showed extremely positive results, with 99.2% of the children showing extreme enthusiasm toward their interaction in the waste-sorting game and 97% of the students identifying themselves as “ocean helpers” (Figure 11). Though these figures are merely reflections of how clearly and enthusiastically the children responded, they are supported by evidence in the literature that interactive environmental education can increase awareness. Therefore, these results may be taken as indications for further programs that are planned where knowledge tests would be incorporated.

The effectiveness of these interventions is consistent with research showing that action-oriented, participatory environmental education during childhood significantly strengthens sustainable behavior trajectories over time (Chawla and Cushing, 2007; Ardoin et al., 2015). Teacher observations further support the value of contextualized place-based learning approaches in strengthening environmental literacy and responsibility (Ardoin et al., 2015). Posters (Figure 12) were also produced for wider education and enlightenment in the communities for environmental consciousness, and stewardship was well-received.

Policy and institutional advancements

Delivery of key policy outputs and national-level knowledge products

Guyana-PROMAR generated significant early achievements in strengthening Guyana's national policy and institutional frameworks for marine litter prevention and plastic waste management. A major milestone was the successful development of a national Policy Brief (Figure 13a), which was finalized and formally shared with the Environmental Protection Agency (EPA). The policy brief, developed with technical support from adelphi, represents an important step in translating project evidence into actionable governance recommendations. Policy briefs are widely recognized as effective instruments for bridging the science-policy interface and enabling informed environmental decision-making, particularly in the context of emerging marine pollution challenges (United Nations Environment Programme, 2021; Vince and Hardesty, 2017). In addition, Guyana-PROMAR completed the draft Extended Producer Responsibility (EPR) Framework (Figure 13b) and Draft National Deposit Refund Scheme (DRS) for Plastic Bottles and Plastic Packaging in Guyana (Figure 13c), marking a substantial contribution toward institutionalizing upstream approaches to plastic pollution control. EPR systems are increasingly promoted as critical policy mechanisms for shifting responsibility for post-consumer waste from municipalities to producers, thereby incentivising eco-design and sustainable product lifecycles (Organisation for Economic Co-operation and Development, 2016; Dauvergne, 2018). The initiation of work on a Deposit-Refund Scheme further reinforces Guyana's movement toward circular economy-aligned waste governance.

National dialogue and capacity building as mechanisms for stakeholder alignment

Another central achievement of Guyana-PROMAR was the successful convening of high-level multi-stakeholder engagement events in May 2025. The National Dialogue on Marine Litter Prevention and Plastic Waste Management, held on 21 May 2025, provided a structured platform for aligning government agencies, civil society actors, and technical partners around national priorities. Such participatory dialogue processes are widely recognized as essential for improving legitimacy, shared ownership, and long-term policy effectiveness in environmental governance (Reed, 2008). This was followed by a Capacity Building Workshop on 22 May 2025, focusing on Extended Producer Responsibility and Circular Economy Business Model Ecosystems. Capacity development is a cornerstone of effective marine litter mitigation, particularly in Small Island and coastal developing states where implementation gaps often stem from limited technical and institutional resources (Hartley et al., 2018; United Nations Environment Programme, 2021). Guyana-PROMAR's training focus on circular business models reflects global consensus that marine litter prevention requires not only awareness but also systemic transformation of production and consumption systems (Ellen MacArthur Foundation, 2016).

Institutional innovation and emerging circular economy infrastructure

Beyond training and dialogue, Guyana-PROMAR advanced institutional innovation through discussions on establishing “Guyana Circle—The Circular Economy Lab of Guyana” (23 May 2025). The development of such innovation platforms is increasingly viewed as critical for enabling experimentation, piloting closed-loop solutions, and fostering cross-sector collaboration in circular economy transitions (Geissdoerfer et al., 2017).

Strengthening data systems and regional monitoring collaboration

A notable achievement under Guyana-PROMAR has been the establishment of collaboration with UNEP-GRID Geneva and the University of Geneva to develop a marine litter data collection, monitoring platform, and regional information system. Enhanced monitoring systems are increasingly critical for supporting evidence-based decision-making and tracking progress toward SDG-linked marine pollution targets (Gacutan et al., 2024). Participation in the Enhanced Data Collection Workshop (May 2025) and the Data Platform Co-Design process (June 2025) signals strong institutional engagement with emerging digital environmental governance approaches. Such integrated monitoring networks contribute to harmonized reporting and strengthen regional cooperation for marine litter prevention in the Wider Caribbean (United Nations Environment Programme, 2021).

Regional learning exchange and knowledge transfer across the Caribbean

PROMAR-Guyana has actively contributed to regional knowledge exchange through participation in major Caribbean and international forums. These include the Dominican Republic study visit (June 2024), the PROMAR Summit in Medellín, Colombia (November 2024), the Coastal Zone Canada Conference (June 2025), and the Caribbean Water and Wastewater Association Conference in Belize (October 2025). Engagement in such platforms strengthens transboundary learning, enhances access to best practices, and builds networks essential for addressing marine litter as a shared regional challenge (Vince and Hardesty, 2017). These exchanges also catalyzed stronger partnerships between government, academia, and civil society actors, reflecting the collaborative governance approaches increasingly required for complex marine pollution problems (Reed, 2008).

Synthesis and lessons learned

The findings demonstrate that systematic, community-based circular economy interventions can deliver measurable reductions in plastic leakage while simultaneously fostering behavioral, social, and institutional change. Our study extends the conceptualization of circular economy application by showing that interventions with low technology levels and a strong sense of community can surpass technical measures in effectiveness when accompanied by behavioral mechanisms and polycentric governance. Validation of the source-pathway-receptor framework in the context of a data-poor flood-prone coastline provides a replicable approach to measure plastic leakage and assess intervention effectiveness. Guyana-PROMAR highlights several critical lessons: drainage systems represent key leakage pathways requiring targeted action; incentive-based recovery mechanisms can effectively motivate participation; and technical interventions are most impactful when aligned with sustained education, stakeholder engagement, and supportive policy reform. The integrated approach—combining monitoring, cleanup action, youth innovation, and school-based learning—reinforced awareness, strengthened pro-environmental attitudes, and stimulated behavioral intentions across diverse demographic groups, consistent with evidence that participatory, multi-channel strategies outperform standalone awareness campaigns (Reed, 2008; Hartley et al., 2018).

Despite strong early success, limitations remain. Reliance on short-term self-reported feedback and secondary monitoring data constrains assessment of long-term behavioral persistence and ecological impact, underscoring the need for longitudinal evaluation and follow-up monitoring. Implementation also faced governance challenges, including slow institutional response timelines and limited stakeholder representation during key national events, reflecting common barriers in developing policy contexts (United Nations Environment Programme, 2021). Nevertheless, Guyana-PROMAR's collaborations, contributions to legislative reform, and engagement with regional monitoring frameworks provide a robust foundation for scaling marine litter prevention in Guyana. Sustained financing, regulatory support, and inclusive stakeholder participation will be essential to replicate and institutionalize this model as part of comprehensive coastal environmental management and SDG-linked marine debris monitoring (Gacutan et al., 2024).

Furthermore, the observed relationship between changes in KAP, non-monetary incentive systems, and prolonged involvement will help enrich the behavioral economics discourse on environmental management in low-income environments. The research helps gain an insight into the mechanics behind implementing circular economy transitions in regions with limited waste management facilities, owing to the use of household materials flow, drainage interception indicators, and collaborative policymaking frameworks.

This study demonstrates that a systematic, circular economy-based approach can deliver tangible and socially inclusive solutions to the persistent challenge of marine litter in vulnerable coastal environments. Through the implementation of the PROMAR project in Guyana, the research provides empirical evidence that plastic pollution along the coast is predominantly land-based, strongly linked to drainage networks, and driven by structural gaps in waste management systems. By targeting these source-pathway linkages, the project moved beyond conventional clean-up models toward prevention-oriented interventions capable of reducing plastic leakage at its origin.

This study contributes to implementation science for circular transition by showing that technological solutions can produce sustainable effects only through their integration into behavioral nudges and polycentric governance structures. From a methodological perspective, this study provides a replicable model for applying MFA and statistical analyses to data-poor coastal settings.

The results confirm that community-level waste interception, decentralized waste-to-value hubs, and incentive-based recovery schemes can collectively achieve measurable reductions in plastic flows into aquatic and marine environments. The dominance of PET, HDPE, and other packaging plastics in intercepted and collected waste streams underscores the relevance of upstream policy instruments, particularly Extended Producer Responsibility (EPR), as a critical mechanism for sustaining and scaling marine litter prevention efforts. Importantly, the findings show that technical interventions alone are insufficient; their effectiveness is contingent on parallel investments in education, behavioral change, and stakeholder participation.

A key contribution of the Guyana-PROMAR pilot lies in its integrated implementation framework, which combined material flow analysis, citizen-science monitoring, and community engagement with institutional dialogue and private-sector collaboration. The partnership between the University of Guyana, local communities, and national agencies illustrates the value of multi-actor governance arrangements in addressing complex environmental challenges. Such collaborations enhanced data credibility, strengthened local ownership, and improved the feasibility of translating pilot outcomes into policy-relevant insights.

In a broader regional context, some of the transferable lessons derived from the study's approach include: (1) the significance of drainage systems as leverage intervention sites where slight technological alterations result in significant decreases in leaks; (2) non-monetary and community incentives that ensure sustained participation despite limited resources; and (3) leveraging interventions through existing social infrastructure. The focus on drainage systems as critical control points, the use of modest non-cash incentives to reinforce source separation, and the anchoring of interventions within existing community structures collectively form a replicable model for marine litter prevention. When aligned with national waste strategies and regional policy frameworks, these approaches can contribute meaningfully to reducing plastic pollution while supporting livelihoods and community resilience.

Nevertheless, the study also highlights the need for sustained monitoring and institutional commitment to consolidate gains achieved during pilot phases. Long-term success will depend on embedding circular economy principles into national regulations, securing stable financing mechanisms, and expanding recycling and recovery markets. Future research should therefore prioritize longitudinal assessments of plastic leakage reduction, behavioral persistence, and the effectiveness of policy instruments such as EPR once fully operational.

In a succinct, the PROMAR project implementation in Guyana demonstrates that marine litter prevention is both technically feasible and socially achievable when addressed through a systematic, prevention-focused, and participatory framework. By integrating local action with regional and global sustainability agendas, the project provides a robust evidence base to inform policy, guide replication, and advance the transition toward circular and resilient coastal waste management systems in the Caribbean and beyond.