Stakeholders’ Views on a Decadal Evolution of a Southwestern European Coastal Lagoon

Abstract

Addressing environmental challenges requires the inclusion of local communities with relevant knowledge of the social–ecological system in which they are embedded, in addition to using transdisciplinary approaches that are critical to the co-production of successful and sustainable environmental solutions. A qualitative methodology was used to examine stakeholders’ views of decadal changes in Ria de Aveiro, a coastal lagoon on Portugal’s Atlantic coast. Seven focus groups were conducted, which included 42 stakeholders from coastal parishes, in order to obtain identical geographical representation with a study conducted a decade ago. Participants represented a diverse sample of groups interested in or affected by management options and activities in the lagoon system and were asked to reflect on the main changes that occurred over the last decade. Positive changes reflected an increase in the levels of environmental awareness, a positive trajectory of the environmental status of Ria de Aveiro, and a decrease in illegal fishing activities. Persisting concerns referred to the lack of an efficient management body for Ria de Aveiro, pressures related to changes in the hydrodynamic regime of the lagoon, the disappearance of native species and increase in invasive alien species, the abandonment of traditional activities (e.g., harvesting of seagrass and seaweed, salt production, agriculture in lagoon margins, and artisanal fishing), and the degradation and lack of maintenance of salt pans. Our findings highlight the importance of longer-term transdisciplinary and social–ecological research and illustrate how stakeholder views regarding the shortfalls of the movement towards the integrated management of ecosystems remain.

1. Introduction

Environmental challenges in coastal areas are complex and deeply connected to human behavior, especially since they interlink with societal challenges such as economic growth and communities’ welfare and well-being. To develop successful and sustainable solutions, knowledge and collaboration from different stakeholders, including citizens, are needed [1,2]. Involving stakeholders ensures that diverse perspectives and interests are acknowledged, fostering the co-production of knowledge that moves beyond problem analysis to define shared goals, norms, and visions for effective interventions, while considering potential conflicting interests and trade-offs. Collaboration between researchers and societal actors reinforces the legitimacy, sense of ownership, and accountability of the coastal management process [3]. This approach is indicated to address socially relevant challenges, encourage mutual learning, and generate actionable knowledge that is both scientifically rigorous and practical for societal application [4]. When policies and strategies reflect local needs, they are more likely to be successful and complied with by the population [5,6]. Considering that local communities have relevant knowledge of the social–ecological system in which they are embedded, it is critical to involve them in the co-production of knowledge [7,8].

The management of ecosystem often faces social and political obstacles (for example, resistance to change, compliance issues, communication, and lack of resources) as the measures that are implemented do not always take local social and cultural values into account (e.g., hard infrastructure solutions, restoring wetlands, elevating structures) [9]. To avoid and overcome such obstacles, a transdisciplinary and social–ecological perspective of natural ecosystems should be applied, as it enables partnerships among stakeholders to be formed, trust to be built, the amplification of missing voices, levels the power imbalance, and can act as a motivator towards pro-environmental behavior [10,11,12,13].

Previous research has demonstrated the importance and value of increasing public participation in development and management processes [14,15,16]. However, very few studies include the local community throughout the process, as stakeholder engagement is often performed in a very superficial and ad hoc manner. Consequently, the social legitimacy and effectiveness of the management measures are undermined and can ultimately be compromised. Stakeholder knowledge can be not only complementary to scientific knowledge—as it offers social perceptions and public experiences of those directly affected by the ecosystem—but can also assure societal relevance, enhancing the accuracy of environmental decisions [17,18]. Therefore, the co-production of knowledge allows for the combination of diverse perspectives and creates solutions that are more context-specific and increasingly likely to succeed, e.g., [19,20].

Portugal’s location in the Mediterranean biogeographic region increases its exposure to climate change challenges like those faced by Mediterranean basin countries, such as increased heat waves and water scarcity. At the same time, Portugal’s exposure to the Atlantic Ocean subjects it to high-energy events such as intense storms and coastal erosion. These multiple stressors make Portugal one of the European countries with the highest vulnerability to climate change, despite efforts to implement mitigation and adaptation measures, e.g., [21,22,23]. Coastal communities are particularly at risk, as Portugal has an extensive and highly populated coastline and faces a significant threat from sea level rise [21,22].

Using Ria de Aveiro, a coastal lagoon, located on the Atlantic coast of Portugal, to serve as a methodological case study, a qualitative focus group study was carried out, which aimed to examine stakeholders’ views of decadal changes in the ecosystem. Local communities’ well-being, and in some cases, livelihoods, depend on the lagoon ecosystem. Therefore, their views and experiences constitute a crucial element in environmental, social, and economic sustainable management. By analyzing local stakeholders’ views and experiences, and comparing them with stakeholders’ views a decade ago, we offer fresh insights into how local knowledge at ecological, social, political, and economic levels changed over time and how this may influence local communities’ support and involvement in Ria de Aveiro’s governance and integrated management. To this end, focus group discussions were complemented with the spatialization of both areas of concern and areas considered positive or beneficial, supported by maps of Ria de Aveiro.

Effective stakeholder engagement is crucial for the collective management of natural resources, especially in complex socio-ecological systems such as the Ria de Aveiro [24]. Pretty [25] highlights the role of social capital—including trust, shared norms, and social networks—in enabling communities to work together in resource governance.

Strong social ties enhance cooperation, foster mutual accountability, and facilitate the co-creation of sustainable management practices. In this context, fostering stakeholder participation is not only a means of improving decision-making legitimacy but also a pathway to long-term ecological and socio-economic resilience. Integrating local and scientific knowledge can further enhance participatory governance. When diverse actors, including policymakers, researchers, and local communities, engage in knowledge co-production, they contribute to a more inclusive and adaptive management process. Strengthening social capital within the governance framework of the Ria de Aveiro can therefore lead to more robust and enduring solutions to environmental challenges.

Participatory and multi-level approaches are particularly relevant in complex systems like Ria de Aveiro, where effective management depends on cooperation between policymakers, researchers, local communities, and industry actors. Participation strengthens stakeholder commitment, leading to more effective and sustainable governance. However, its success depends on meaningful engagement, clear decision-making structures, and coordination to ensure adaptive and responsive environmental management [26].

Ria De Aveiro Socio-Ecological System

Ria de Aveiro, located in the Centro Region of Portugal, is a shallow coastal lagoon covering circa 75 km², characterized by its dynamic interaction between natural capital and cultural heritage. The lagoon branches into several channels: Mira and Ílhavo to the south, Espinheiro and Murtosa to the east, and the S. Jacinto–Ovar channel to the north. The Espinheiro channel, which overlaps with the estuary of the Vouga River, the main freshwater source of the lagoon, creates a salinity gradient from the agricultural lands of Baixo Vouga Lagunar to the sea boundary at Barra, marked by a distinctive lighthouse. The region is densely populated, containing 11 municipalities and 74 parishes with over 367,000 residents. It plays a relevant role in the socio-ecological identity of the region, integrated into the Natura 2000 Network for its rich biodiversity. This includes habitats like salt marshes, seagrass meadows, and dune systems, which support a diverse array of species, from economically significant fish such as cuttlefish, shellfish, and crustaceans to migratory and resident bird populations. Besides its ecological importance, Ria de Aveiro has been paramount for economic and cultural heritage that has shaped the local communities for generations. Like many coastal areas, maritime traffic, harbor logistics, boating tourism, recreational activities, aquaculture, small-scale fisheries, bait digging, hunting, aquatic sports, beach going, agriculture, livestock, and industrial enterprises are all activities that occur, sometimes with conflicting interests in the lagoon area. As a common vision, it is acknowledged that the natural capital and ecosystem services it provides are pivotal for the region’s sustainable development. Due to the variety of organizations and entities involved in Ria de Aveiro’s governance, its political and management contexts become an additional challenge.

2. Materials and Methods

Following the participatory approach applied one decade ago [27], focus groups were used to engage stakeholders and citizens to communicate with the Ria de Aveiro end-users and to identify remaining and new challenges, conflicting interests, concerns, and positive changes. Focus groups dynamically explore the views of diverse stakeholders and help disclose more concealed attitudes that extend past the perspectives collected in individual interviews [28]. In this context, views refer to opinions, attitudes, or beliefs that individuals hold about a particular topic, issue, or situation. To enable the analysis of the decadal evolution, seven focus groups were created that included stakeholders of the same coastal parishes, which, specifically, are as follows: FG1—Union of Parishes of Glória and Vera Cruz; FG2—University of Aveiro; FG3—São Jacinto Parish; FG4—Gafanha da Nazaré Parish; FG5—Torreira Parish; FG6—Murtosa Parish; and FG7—Hunters and Fishermen’s Association of Avanca [Figure 1]. These were created to obtain an identical geographical representation to the study conducted a decade ago [27]. Additionally, participants were required to have lived in the region for at least the ten years that are covered in the study.

The difference between the number of focus groups in 2013 and 2024 is a result of the merging of the Glória and Vera Cruz parishes to create the Union of the Parishes of Glória and Vera Cruz as part of an administrative reorganization in Portugal that took place in 2013. The focus groups were created with the support of the president of each parish; parishes correspond to administrative subdivisions of a municipality. Participants were invited to sign a consent form for free and informed participation and to authorize the audio recording of the session. Focus groups were organized in a semi-structured format, with a common script to obtain answers from the groups that could be compared; however, there was some openness so that the discussion could flow in different directions according to the experience of each group. For the analysis of stakeholders’ views on the decadal evolution, participants were invited to reflect on the main changes that occurred in Ria de Aveiro over the last decade. To complement the discussion, and following [27], participants were provided with a map of Ria de Aveiro and invited to identify three areas that elicited concerns (red dots) and three areas that they considered positive or that brought benefits (green dots). This approach enabled the spatialization of the stakeholders’ and citizens’ views. Additionally, a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis was conducted. SWOT is a widely used strategic planning and management tool designed to help businesses, industries, or organizations assess their current position and develop informed strategies. A typical SWOT analysis involves the identification of internal strengths and weaknesses along with external opportunities and threats.

2.1. Participants

The focus groups with local citizens of coastal parishes had an average of 6 participants per session. The number of participants was kept below 10 to not compromise the discussion’s depth [29]. A sample of 42 stakeholders (83% men and 17% women, assuring a similar gender distribution to a decade ago (80% men and 20% women [27])) took part in the focus groups conducted between April and July of 2024. The inequality in favor of the presence of men is due to men being representative of most local activities in Ria de Aveiro (e.g., fishing, extraction of biological resources (shellfish, worms, seagrass, etc.)). Participants were aged between 26 and 84 years old (M = 57.45, SD = 14.72). Stakeholders included a diverse array of groups and individuals who have an interest in or are affected by management options and activities in Ria de Aveiro (e.g., 12% government, 7% regulatory agencies, 47% members of associations and NGOs, (including fishermen and hunters), 7% private sector, 12% academia, and 15% residents) and belonged to the same areas of activity to assure a similar thematic representation of stakeholders [27].

2.2. Procedure

Participants were recruited through invitations sent by the parishes and via social media. Focus groups lasted between 90 and 120 min. The scheduling and setting of the focus groups were organized considering participants’ availability and held in local spaces known to the community. Focus groups were moderated by one of the researchers, while another researcher took notes and asked follow-up questions. Each focus group began with the moderator welcoming participants, followed by a brief description of the purpose of the study, its importance, the voluntary nature of participation, and the confidentiality of responses. At the end, all participants were debriefed and thanked for their participation.

2.3. Analytic Strategy

Focus group transcripts were audio recorded, transcribed verbatim, and anonymized. Transcripts were then iteratively coded. Data was analyzed through a process of thematic analysis, which involves the identification, analysis, and reporting of common themes to manage and support interpretation of the data [30]. As a first step, familiarization with the data occurred through repeated readings of the transcripts. Significant aspects of the data were then systematically coded, and notable extracts were grouped under each code. Codes were then organized into potential themes, which were further reviewed. The initial themes were refined, and commonalities and differences within and across the right focus groups were examined (see

Table 1. Themes and sub-themes.

Themes	Sub-Themes
Positive Changes	Improvement of environmental conditions
	Higher environmental consciousness and compliance
	Structural improvements
Changes Worthy of Concern	Integrated management of Ria de Aveiro
	Hydrodynamic changes
	Biodiversity
	Tourism and water sports

for an overview).

In the Ria de Aveiro map, the red and green dots, representing, respectively, areas of concern and positive or brought benefits, as classified by the participants, were georeferenced using QGIS 3.34.10-Prizren on a WGS 1984 geographic coordinate system. The points that elicited concerns were classified as 0, and the positive/beneficial points were classified as 1. This information was further interpolated as a 20 × 20 m grid raster (Inverse Distance Weighted interpolation, P coefficient = 2, extended to coordinates −83,638.8566, −13,159.3691, 78,449.0514, 149,980.7144 [EPSG:3763]). The same procedure was applied to data from 2013 focus groups [27] when the same question was raised. Changes in the view (positive or concerns) from 2013 to 2024 were assessed by subtracting the interpolation surface from 2013 to the one from 2024 using the Raster Calculator tool 2025, and the output raster was classified to highlight the change of views between 2013 and 2024, with the red indicating a shift towards a concern (−1) and the green denoting improvement of the opinion (+1), while the lack of change (0) was classified as transparent pixels. The areas where the opinion was maintained between 2013 and 2024 were assessed by summing the original interpolation surfaces. This output raster was classified between 0 and 2 and was highlighted with the purple color showing the persistent concern (pixels values closer to 0) while the yellow was associated with persistent positive values (pixels values closer to 2). The values around 1 correspond to the areas where change occurred and, therefore, were kept transparent. The base map was provided by MapTiler Planet 2025 (https://api.maptiler.com/, accessed on 26 February 2025).

3. Results

Participants were prompted to discuss their views and experiences on how Ria de Aveiro changed over the last 10 years. At the end of each session, to complement the discussion, and following Sousa et al.’s [27] methodology, participants were provided with a map of Ria de Aveiro and invited to identify three areas that elicited concerns (red dots) and three areas that they considered positive or brought benefits (green dots) [see Figure 2 and Figure 3]. This approach enabled the spatialization of the stakeholders’ views.

Most stakeholders identified positive changes from the past decade in the following aspects:

• Improvement of environmental conditions

Participants referred to an improvement in environmental conditions, particularly the water quality, considering it to be less contaminated with herbicides, metals (e.g., mercury), and other pollutants from the industry. Most participants also considered that there had been a reduction in litter at the lagoon (inside the water and surrounding areas). Because of those improvements and restrictions on hunting, participants recognized an increase in biodiversity, such as a rise in the population of the purple heron Ardea purpurea, Eurasian otter Lutra lutra, flamingo Phoenicopterus roseus, and the expansion of Salicornia ramosissima and Sarcocornia perennis. This view was also georeferenced in Ria de Aveiro’s map [Figure 2a] as the biggest green area surrounding Estarreja (Esteiro de Estarreja and Largo do Laranjo). Nonetheless, some participants still considered marine litter and water pollution (e.g., use of pesticides in agriculture) to be a present concern.

• Higher environmental consciousness and compliance

A rise in environmental consciousness was noted as a positive change over the last decade, meaning a higher level of understanding and sensitivity towards the environment and active commitment to protecting it. Participants viewed younger generations in particular as more environmentally conscious. Among fishermen, participants also denoted a greater awareness, respect, and compliance with rules and regulations regarding fish size, fishing techniques, number of fish kept, but also a reduction in marine litter left at the ocean and the lagoon. Additionally, participants considered the increase in research about Ria de Aveiro not only as a positive change but as a contributing factor to higher awareness of residents regarding the cultural heritage, socio-economic and ecological importance, and the value of the lagoon.

• Structural improvements

Structural improvements were noted, including new light signaling in the lagoon channels, which according to participants reduced the number of accidents and brought significant improvements to navigation. This is consistent with the georeferencing results [Figure 2a], where green areas can be seen along the lagoon channels.

Stakeholders also identified changes that they considered worthy of concern. These were as follows:

• Integrated management of Ria de Aveiro

Participants expressed concerns about the inefficient integrated management of Ria de Aveiro, feeling very minimal progress in this area. Participants felt that a local integrated management body that would include different stakeholders (academia, government, business, regulatory agencies, and citizens) was essential to the effective management of Ria de Aveiro. Barriers to the effective management of the lagoon, according to the participants, were the shared responsibility of 11 municipalities, with conflicting interests of the different entities involved, the interests of major economic groups prevailing over the interests of the smaller users of the lagoon, and a lack of accountability for the consequences of decisions made.

• Hydrodynamic changes

As a result of dredging in the lagoon to improve the port activity, participants referred to hydrodynamic changes, including the siltation of navigation channels and the increase in tidal prism (lower water level during low tide and higher during high tide). Climate change impact, particularly its effects on coastal erosion and flooding, was also mentioned by participants as a concerning issue that has been aggravated over the last decade. Flooding has led to damage to people’s homes, the salinization of agricultural land (rice fields in particular), and the disappearance of salt pans and salt marshes. These results are also shown in Figure 2a, where the georeferencing with red areas on the Atlantic coast and the Ovar/S. Jacinto channel were attributed to the concerns surrounding erosion, dredging, and hydrodynamic changes in the lagoon.

• Biodiversity

The loss of habitats (such as seagrass Zostera noltei and Zostera marina, and saltmarsh reeds) and biodiversity (with the disappearance of species of crickets and frogs), as well as a reduced abundance of fish and shellfish (e.g., European eel Anguilla anguilla, sole Solea solea, lamprey Petromyzon marinus and Lampetra planeri, shad fish Alosa fallax and Alosa alosa, cuttlefish Sepia officinalis) were also concerning trends identified by the participants. Additionally, a rise in invasive species, namely, pampas grass Cortaderia selloana, common water hyacinth Eichhornia crassipes, Manila clam Ruditapes philippinarum, Louisiana crawfish Procambarus clarkii, acacia Acacia longifolia, and great cormorant Phalacrocorax carbo, were mentioned as concerning changes over the last 10 years. New techniques and the illegal harvesting of seafood, including the use of destructive fishing gear, were mentioned as factors that contribute to biodiversity loss.

• Tourism and water sports

Participants had conflicting views on the decadal growth of tourism. On one hand, they recognized the economic benefits to the local economy and considered the increase in the number of people practicing water sports (e.g., kite surfing, stand-up paddle, sailing) in Ria de Aveiro as a tool for regional development on economic and social levels. On the other hand, they considered tourism in the central channels of the lagoon to be excessive, and the growth of the sector to have had a negative impact on Ria de Aveiro. For example, strong currents inside the lagoon and the waves caused by boat movements were associated with the erosion of the saltpan walls; therefore, pressures related to increased tourism are perceived as aggravating the natural erosional processes.

Stakeholders’ views of the geographical areas that were considered positive or raised concerns have changed throughout the study area from 2013 to 2024. Figure 2a shows several clusters identifying the inversion of opinions. While the improvement, i.e., the change from a concerning to positive opinion, was found to be mostly associated with the distal areas of the lagoon (e.g., improvement of environmental quality in Estarreja channel), degradation hotspots were identified at the central water body, closer to the city of Aveiro, which can be linked with human use and urbanization of such areas, and in areas usually located on the eastern margins of the channels. The respondents associated these degradation spots with the siltation or erosion of the channels, or flooding, because of interventions in the lagoon bed that have influenced hydrodynamics and high-energy weather events. Ultimately, the loss of the saltpan’s walls due to abandonment and the erosion of small islands in the central channel was a concern that was frequently associated with hydrodynamic changes. However, there are areas where the opinion has not changed during this decade [Figure 2b], maintaining the concerns related to the hydrodynamic changes and dredging of the lagoon, and a positive trajectory of the water quality improvement and the cultural and social value of the lagoon, even after a decade.

4. Discussion

Stakeholders’ views of decadal changes in the Ria de Aveiro coastal lagoon were expressed as a narrative complemented by spatially explicit information.

• What was perceived as positive and remains with a positive view

A ten-year positive trajectory was identified in the environmental conditions of Ria de Aveiro. This is also reflected in Figure 2 by the biggest green area surrounding Estarreja (Esteiro de Estarreja and Largo do Laranjo). For decades, this area was under stress due to the presence of a chlor-alkali plant in the Estarreja Chemical complex, which was a source of large amounts of mercury and other metals and metalloids until 1994, when the plant stopped the release of effluents to the channel [31]. As a result of this measure, the environmental quality of this area has improved both environmentally and biologically [32], and this has been identified by the respondents. In that sense, the 10-year gap allowed a change in community signaling from a concern area to an area associated with a positive view [Figure 2]. This change in view was also associated with the signing of the concept of an industrial and business sustainable development plan brought by the Eco-Business Park in Estarreja and the positive impact of the BioRia project (implemented by the municipality with the aim of preserving nature and biodiversity and providing environmental education). Moreover, the intense smell in the city channels in low water and the direct discharge of untreated domestic sewage in one of the city channels were previously identified as concerns [27], while currently those concerns no longer apply and were seen as resolved as a consequence of the implementation of a multi-municipality sanitation system with secondary treatment since 2005 [33].

• What was perceived as positive and became a concern

Tourism, specifically ecotourism, was viewed as a positive activity by stakeholders ten years ago [27]. In 2024, the increase in tourism changed this view to some degree, as stakeholders considered the negative consequences associated with the general growth of tourism (e.g., pressures on the ecosystem and infrastructure). The coastal area was previously viewed as exclusively positive [Figure 3a], and in 2024 [Figure 3b], this view shifted, as indicated by the absence of green dots. Similarly, in other coastal regions, the social, cultural, and environmental impacts due to the expansion of tourism have been predominantly regarded as being of increasing concern [34,35].

• What was perceived as a concern and acquired a positive view

Progress in environmental consciousness, meaning an increase in the levels of environmental awareness, was identified by the participants. Therefore, local knowledge about the area’s environmental conditions was obtained, confirming effective environmental concern. Locals considered this to be particularly salient among younger generations. This is consistent with research conducted in Portugal and other countries [36,37].

Societal challenges identified by local stakeholders a decade ago [27] referred to the lack of investment in tourism versus the touristic potential of Ria de Aveiro. Currently, participants describe a considerable increase in the tourism sector at the regional level. This view is consistent with official data, which demonstrates that the number of local accommodations/lodgings in Aveiro went from 30 to 2500 over the last 10 years, and tourism levels consecutively broke records, reaching approximately 447,000 overnight stays in 2023 [38]. The dual impacts of tourism identified by participants had a positive impact on the local economy and development but also increased pressure on the ecosystem and infrastructure (e.g., roads, sewerage, wastewater treatment plant), which remain insufficient to effectively manage the over-tourism during peak seasons. These results are consistent with previous research carried out with Aveiro residents [39,40]. Comparably, tourism is recognized as exerting a dual impact on other coastal regions. Although it contributes significantly to economic growth and often constitutes the primary socio-economic activity within coastal communities, it also represents one of the most substantial anthropogenic pressures affecting these environments [34,39,41].

Other concerns expressed 10 years ago [27] regarding illegal fishing activities continue to diminish. This could partially be explained due to recent Portuguese legislation on fishing activity, fishing gear, and measures for the conservation and sustainable exploitation of marine biological resources [42]. While the lack of aids to navigation on the channels was a concern back then, now this appears to have improved significantly, according to stakeholders. This is consistent with the georeferencing results that can be observed along the lagoon channels [Figure 2a and Figure 3], particularly in the northbound direction above the central channel.

The results also show that there was a change of view from concerning to positive in the distal areas of the lagoon (e.g., the improvement in the environmental quality in the Estarreja channel). Some areas of concern were associated with the siltation or erosion of the channels or flooding, because of interventions in the lagoon bed that have influenced hydrodynamics and high-energy weather events [43].

• What was perceived as a concern and remains a concern

Persistent challenges refer to the lack of an efficient management body for Ria de Aveiro, an area where participants felt that there was little to no improvement. Ria de Aveiro is governed by a complex network of public agencies operating at various levels, each with distinct responsibilities [44]. Shaped by both European and national legal frameworks, the area is subject to numerous policies, plans, and programs intended to define objectives and implement protection measures across multiple government sectors. However, the fragmentation of decision-making, spread across 11 municipalities and overlapping jurisdictions, has made it consistently difficult to develop coherent, integrated management strategies for the estuarine ecosystem [45]. In this context, the concept of sustainability remains highly contested among the various actors involved. Additionally, the ongoing restructuring of central administration authorities has, in recent years, undermined efforts to decentralize decision-making and engage local stakeholders more effectively [45]. The Intermunicipal Community of the Aveiro Region (CIRA) is a public institution that functions as an administrative division in Portugal. It was officially created in 2008 to promote and coordinate common interests among the municipalities it encompasses [46]. In 2011, with the launch of the “Green Paper” as part of local government reform, CIRA was selected as one of two intermunicipal communities to lead a pilot study aimed at defining new competencies for these local government structures. In 2013, the same year the first focus group study [27] was conducted, a statute for intermunicipal entities was also established, outlining the legal framework for the transfer of powers from the state to local authorities and intermunicipal communities, defining the legal regime for governing local associations [46,47]. Despite progress towards a municipal community-based compliance model, it is still regarded as poorly understood, overly complex, inefficient, and with weak accountability mechanisms [45,47]. Therefore, stakeholders seem to believe that the current model should be developed further to achieve a more efficient integrated management of the lagoon. This concern is common to other coastal lagoons across different coastal ecosystems [48,49,50]; at the Vistula Lagoon, for example, the integrated management of waters regarding navigation, water quality, fisheries, and tourism is challenging due to its location and the authorities involved [51].

Stakeholders’ views regarding barriers have remained the same over the decade [27]. These include conflicting interests by different entities involved, interests of major economic groups prevailing over interests of small users of the lagoon, and a lack of accountability for the consequences of decisions made. Participants continue to feel the need for an integrated management body for Ria de Aveiro, which despite being covered by a set of plans and programs at various levels (national, regional, inter-municipal, and municipal) [2,49], continue to not include different stakeholders with interests in Ria de Aveiro.

Changes in the hydrodynamic regime have been previously identified as pressures [50], e.g., they remain as pressures mentioned previously by stakeholders and were identified in Figure 2a with red areas along the Atlantic coast, Gafanha da Nazaré, São Jacinto, and Murtosa. This is in line with research predictions that flooding would cause soil salinization, loss, or migration of salt marshes, reeds, and rush marsh habitats and that the frequency and intensity of floods would be aggravated by climate change [49]. Moreover, increases in tidal range and water speed [49,52] contribute to the erosion of the lagoon’s banks and channels and the loss of salt marsh and seagrass habitats. The concerns related to hydrodynamic changes and the dredging of the lagoon have been aggravated by the recently approved interventions intended to improve shipping access to the port.

Changes in biodiversity, such as the reduction in abundance of native species, including fish and shellfish with commercial value (e.g., European eel Anguilla anguilla, sole Solea solea, lamprey Petromyzon marinus and Lampetra planeri, or cross-cut carpet shell Ruditapes decussatus) and the increasing number of alien species with invasive potential (e.g., grooved carpet shell or Manila clam Ruditapes philippinarum, pampas grass Cortaderia selloana, water hyacinth Eichhornia crassipes, Louisiana crawfish Procambarus clarkii), remain concerning issues for locals.

These pressures are identified not only in European coastal systems but also worldwide; for example, there are (a) challenges related to biodiversity loss [53] which are reported widely across different geographic regions and taxonomic groups [54]; (b) loss of commercial fish species due to habitat loss [55], such as Anguilla anguilla populations in Europe which have been in decline since the 1980s [56], or the sole (Solea solea), which is affected by estuarine habitat loss [55]; and (c) estuaries as invasion hotspots due to the activities that take place in these areas such as shipping and boating, aquaculture or recreational and professional fisheries [57,58]. Information provided by stakeholders represents a valuable source for tracking historical socio-ecological data [59] and should be integrated into the surveillance plan for invasive alien species and the monitoring of habitats and associated biodiversity to ensure effective and participatory management.

Other enduring concerns are the abandonment of traditional activities (e.g., harvesting of seagrass and seaweed, salt production, agriculture in lagoon margins, artisanal fishing) and the degradation and lack of maintenance of salt pans. Greater tourism pressures, abandonment of traditional activities, and changes in the landscape can contribute to the loss of the coastal and maritime cultural heritage in Ria de Aveiro. This process is comparable to what is happening in other European coastal regions, namely the Small Isles (Scotland) and Marsaxlokk (Malta) [39], as well as outside Europe, namely, Miyagi in Japan [60].

As part of the discussion and like the results obtained a decade ago [27], participants made suggestions for improving the identified concerns. Participants suggested changes to the current model of management of Ria de Aveiro, suggesting that an integrated management body formed by different stakeholders be created (academia, governance, business, regulatory agencies, and citizens, with representation from end-users of the lagoon). This entity would include public consultation as an integral process for decision-making, so the interests of all users would be considered, and votes would be held on important decisions. Accountability for environmental impacts, and responsibility for implementing mitigation measures, were recommended for entities whose activity would affect the lagoon ecosystem and consequently affect different activities on which the livelihood of end-users depends.

Finally, environmental literacy was proposed to strengthen environmental awareness and citizen action and participation in pro-environmental behaviors.

Taken together, these results strengthen the accumulating evidence of the relevant role played by the inclusion of local stakeholders and their knowledge in the successful implementation and management of ecosystems [2,27,61]. They further highlight the importance of policies and strategies reflecting local needs being complied with by the population [5,6]. Successful implementation calls for the enhancement of representation and involvement of stakeholders throughout the management process to enable the design and implementation of socially responsive and context-specific policies and increase the quality and effectiveness of environmental decisions.

• How do these compare to other coastal regions?

The trends identified in our study are common to other coastal regions. An improvement in environmental conditions, namely water quality, has also been identified as a common trend in coastal areas in Europe and worldwide. This is due to stronger regulation; for example, EU legislation and effective implementation by member states, and pollution control policies in China, have resulted in fewer pollutants [62,63]. Furthermore, legislation, frameworks, and policies implemented for the environmental conservation of coastal zones has contributed to improved water quality.

Additionally, coastal areas with rich cultural heritage share a common perception of tourism, recognizing it as exerting a dual impact on the regions. On one hand, coastal communities identify the economic benefits and growth related to tourism as largely positive [34,41]. Nonetheless, the seasonal nature of coastal tourism leads to an increase in population during a short period, which exerts negative pressures, visible to local communities, on the coastal infrastructures and ecosystems [64,65,66]. The abandonment of traditional activities (e.g., artisanal fishing, harvesting salt) is a common challenge to different coastal regions, due to global competition, low profitability, an increase in urbanization, and tourism [67]. This is also true in West Africa due to declining fish stocks [68] and in Europe [69] and South America [70] where small-scale fisheries are struggling to survive. Globally, the pressure of industrialized fishing operations poses additional challenges to small-scale fisheries through competition for local resources.

Finally, a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis was conducted to synthesize all the socio-ecological data and information collected and to facilitate understanding of the conclusions that can be drawn from the study [

Table 2. SWOT analysis of long-term socio-ecological research on coastal areas.

Strengths	Weaknesses
- Reflect an increase in the levels of environmental awareness. - A positive trajectory of the environmental conditions and a diminishing of illegal fishing activities. - Stakeholder active engagement. - Sense of place	- Lack of efficient management at coastal lagoons because of non-existence or underperformance of an integrated governance entity. - Pressures related to changes in the hydrodynamic regime due to climate change and large-scale seabed interventions (infrastructure development). - The diminishing of native species and the increase in invasive alien species. - The abandonment of traditional activities.
Opportunities	Threats
- Implemented legislation, frameworks, and policies for environmental conservation of coastal zones at local, national, European and International level (e.g., EU Nature Restoration Law, EU Mission: Restore our Oceans and Waters, Zero Pollution Action Plan, Climate Law and the European Green Deal; UN Decade on Ecosystem Restoration; Sustainable Development Goals; Convention on Biological Diversity; UN Convention on Climate Change; Ramsar Convention on Wetlands). - Long-term commitment and willingness to change of stakeholders to improving socio-economic and environmental conditions of coastal lagoons. - Societal concern and proactivity on environmentally sustainable management. - Environmental literacy programs/funding at local, national, European and International level (e.g., UNESCO/UNEP environmental education, The Greening Education Partnership; the U.S. Global Change Research Program “Climate Literacy: The Essential Principles for Understanding and Addressing Climate Change”; The European Ocean Coalition). - Funding programs to empower local communities (Environmental Fund—UN Environment Programme, Conservation International’s Indigenous Peoples Finance Access Facility, LIFE programme (DG ENV) Horizon Europe).	- Uncertainty related to climate change, namely extreme events. - Global geopolitical tensions and unpredictability. - Uncertainty related to global economy and trade tensions. - Unpredictability of long-term consequences of invasive alien species.

].

5. Conclusions

The current study adds to the body of literature that demonstrates the importance of long-term social–ecological research and its contribution to the restoration and management of coastal areas. It compared local stakeholders’ views and experiences with stakeholders’ views a decade ago, offering fresh insights into how local knowledge at an ecological, social, political, and economic level changed over time and how this may influence local communities’ support and involvement in local governance and management. Opportunities to further support coastal areas are offered by funding programs to empower local communities and national and international environmental literacy programs that are being implemented which can be further developed to enhance ocean literacy and behavioral change towards sustainability. This can be sustained and further enabled by stakeholder active long-term engagement, for example, through citizen science actions, participative workshops, and citizen assemblies, e.g., [25,53].

Overall, our study highlights the benefits of long-term socio-ecological research by integrating ecological and social dimensions through a continuous process of involvement and presents evidence that is globally applicable to the integrated management of coastal lagoons.