The role of legislation, policy and regulation in estuarine management: from an international to a regional scale

Estuaries are increasingly populated due to urbanisation, leading to shoreline alteration, and increase of waste discharge and water extraction. Managing an estuary involves taking into consideration the governance framework, which includes a set of policies and legislation at the international and country level. However, current governance systems do not reflect this which limits their ability to manage competing interests, such as tourism, shipping and conservation. Economic activity often drives estuary governance, but continuous loss of biodiversity and habitats highlights the need for more inclusive governance systems that preserve both, natural and socio-economic capital. Reviewing current governance systems can identify challenges and promote solutions. This study reviews the legislation applied to estuarine systems from an international to a regional scale, using Portugal as a reference case. A ‘horrendogram’ was created to assess legislation which was categorised by the following topics: biodiversity, land planning, water management, marine governance, aquaculture and fisheries, waste management, economic policy, forest management, and climate change. Key challenges include limited coordination between maritime and land planning systems, difficulties in incorporating EU legislation into national frameworks, and fragmented administrative responsibilities. To improve estuarine governance, this study recommends enhancing coordination between administrative bodies, promoting stakeholder engagement throughout decision-making processes, and adopting ecosystem service-based approaches. This approach aligns with the sustainability goals by supporting ecosystem health, enhancing human well-being and promoting sustainable economic growth. The insights developed are applicable to estuarine systems globally, and future research should focus on testing governance systems that integrate ecological, social and economic priorities, while promoting collaboration across administrative bodies and stakeholders. • Estuary governance was not updated to the rapid urbanization in recent years. • Weak coordination between maritime and land planning systems persists. • Challenges in aligning EU legislation and national frameworks. • Ecosystem Service based approaches support sustainable spatial management. • Governance must combine ecology, sociology, economy and intersectoral coordination.