Mangroves are under severe threat – leading to global momentum to increase mangrove protection. Protection can take many forms, from national protection laws to protected areas. Yet the relative effectiveness of these different protection interventions are poorly understood. We present an innovative interdisciplinary approach combining remote sensing, global forest modeling, legal scholarship, and econometrics to quantify the impact of protection on mangrove loss. We reviewed national legal systems for 116 countries containing all of the world’s mangroves, assessing each nation for the presence/absence and strength of protection of national mangrove laws. We found over half of the world’s mangroves are covered by national laws explicitly restricting cutting, clearing or conversion. We classified mangrove cutting restrictions based on level of protection, finding ‘high’ protection — prohibiting cutting or clearing of all mangroves — covered 14% of global mangroves. We used impact evaluation methods to control for confounding effects and attribute changes in mangrove deforestation to national protection laws versus protected areas. Across 52 jurisdictions with mangrove protection laws, between 1996-2020 these restrictions reduced mangrove losses by up to 45%. Protected areas also significantly reduced mangrove loss, but tended to have smaller impacts on reducing rates of mangrove loss in protected areas than national policies. Protected areas reduced mangrove loss by 10% over 1996-2022. In places that did not have national protection policies, protected area impacts on reducing mangrove loss tended to be stronger than countries that had both national protection laws and protected areas. Crucially, however, in places with both protected areas and national protection laws, protected areas do still provide benefits for mangroves. Our results therefore suggest that national protection laws are complementary to protected area approaches.

Marine protected and conserved areas (MPCAs) are promoted as an ecosystem-based adaptation (EbA) approach to increase community and ecosystem resilience to climate change. However, traditional approaches to MPCA design typically do not consider climate risk or habitat condition under a climate threat. We used the Great Sea Reef (GSR) in Fiji as a case study to develop a land-sea prioritization framework that links modeled sediment runoff from rainfall during extreme cyclone events to the probability of coral reefs being in good condition. We incorporated this information in an MPCA prioritization scenario intending to achieve 90% certainty of good-condition coral cover under cyclone risk while minimizing cost to fishers and meeting ecosystem conservation targets. We explored the trade-offs between sites selected for protection, the relative opportunity cost to fishers, and the representation of conservation feature targets between the MPCA scenario that included cyclone risk and a baseline scenario that did not. The cyclone risk scenario's best solution required larger areas of protection (5% more GSR area) than the baseline scenario and additional protection in areas with moderate to high probability of good-condition coral cover. Some areas prioritized for protection in the cyclone risk scenario had relatively high turbidity. Large sections around Vanua Levu were consistently selected for protection across both prioritization scenarios due to high concentrations of all ecosystem conservation features, particularly sea turtle feeding grounds. Overall, the cyclone risk MPCA design had a higher fisher opportunity cost but protected a larger amount of ecosystem conservation features and buffered against habitat condition uncertainty. We explored the potential outcomes of expanding on threat-avoidance and cost-effective conservation prioritization by including habitat responses to threats in the prioritization process. Our findings can inform MPCA design during EbA planning in regions at risk from climate change.

Legal protection of mangrove ecosystems supports biodiversity conservation and climate mitigation and adaptation, but evaluating the global extent and level of protection provided by national mangrove laws is challenging. We assess national laws and policies in the 116 countries that contain all the world’s mangroves and use Bayesian multivariate regression to model the probability of the adoption of mangrove laws based on geopolitical and ecological factors. We find that 82.2% of the world’s mangroves are in jurisdictions with explicit national legal protection. Jurisdictions with a high extent of mangroves that provide significant ecosystem service values are more likely to have mangrove laws; jurisdictions with lower GDP are more likely to employ provisions for community management, environmental impact assessment, and cross-sectoral coordination; those with higher GDP were more likely to include mangroves in coastal planning laws. Our analysis can inform efforts to implement existing laws and target legal reform.

Global projections of ecosystem responses to increasing climatic and anthropogenic pressures are needed to inform adaptation planning. However, data of appropriate spatiotemporal resolution are often not available to parameterize complex environmental processes at the global scale. Modeling approaches that can project the probability of ecosystem persistence when parameter uncertainty is high may offer a way forward. In particular, the conservation of coastal ecosystems with complex dynamics, like mangrove forests, may benefit from knowing where their future persistence is highly probable or, alternatively, cannot be reliably estimated without additional data of appropriate resolution. Here, we simulated network models to make probabilistic projections of the direction of net change in mangrove ecosystems worldwide under the SSP5-8.5 climate emissions scenario by the years 2040-2060. Seaward net loss was the most probable outcome in 77% [37%-78%; 95% confidence interval (CI)] of mangrove forest units, while 30% [15%-59%; CI] were projected to experience landward net gain or stability. In more than 50% of forest units, projections were ambiguous and therefore unreliable, with a near equal probability of net loss or gain. Quantitative models parameterized with locally accurate data could resolve uncertainty in the future persistence of mangroves in places with unreliable probabilistic projections. Projections made under conservation scenarios also showed that, with action to manage or restore, the number of mangrove forest units likely to experience net gain or stability in the future could nearly double. Our approach to simulating ecosystem responses to climatic and anthropogenic pressures provides a clear indication of how certain (or uncertain) ecosystem persistence is and thus can inform conservation planning.

There is a global imperative to upscale restoration in line with the Kunming-Montreal Global Biodiversity Framework. Upscaling of marine and coastal restoration is hindered by legal and governance barriers. Identifying both the types of barriers and potential solutions from global ‘bright spots’ is a first step toward implementing legal and governance frameworks to facilitate upscaling of marine and coastal restoration. Here we identify five types of barriers including (a) lack of fit-for-purpose permitting frameworks, (b) tenure issues, (c) concerns regarding risk and liability, (d) a lack of overarching targets for restoration, and (e) uncoordinated governance frameworks. For each barrier, we conduct a broad analysis of legal and governance solutions from across the world. Our analysis provides a guide for future research and law and governance reform.

Marine protected areas (MPAs) are widely used to conserve and manage coastal resources. Protected areas are governed by a variety of institutional arrangements, yet little is known concerning the relative performance of different governance approaches. This research draws upon a unique dataset that combines details on the reported International Union for Conservation of Nature (IUCN) governance categories of 217 global MPAs and their ecological outcomes to compare the performance of alternative governance arrangements. We find that MPAs with shared governance arrangements, where management authority is shared among multiple government and non-government actors, are 98% more likely to have higher fish biomass than MPAs governed by state agencies (i.e., primarily government) alone (mean effect size and 95% C.I = 0.32 ± 0.31). We also find higher biomass in older MPAs, those in countries with higher gross domestic product (GDP), and those with a higher proportion of no-take area. With targets to protect 30% of our oceans driving new commitments to expand MPA coverage globally, our results suggest that multi-stakeholder participation and collaboration facilitated by shared and decentralized governance arrangements can play an important role in achieving conservation outcomes.

Driven by the United Nations Decade on Restoration and international funding initiatives, such as the Mangrove Breakthrough, investment in mangrove restoration is expected to increase. Yet, mangrove restoration efforts frequently fail, usually because of ad hoc site-selection processes that do not consider mangrove ecology and the socioeconomic context. Using decision analysis, we developed an approach that accounts for socioeconomic and ecological data to identify sites with the highest likelihood of mangrove restoration success. We applied our approach in the Biosphere Reserve Marismas Nacionales Nayarit, Mexico, an area that recently received funding for implementing mangrove restoration actions. We identified 468 potential restoration sites, assessed their restorability potential based on socioeconomic and ecological metrics, and ranked sites for implementation with spatial optimization. The metrics we used included favorable conditions for propagules to establish and survive under sea-level rise, provision of ecosystem services, and community dynamics. Sites that were selected based on socioeconomic or ecological metrics alone had lower likelihood of mangrove restoration success than sites that were selected based on integrated socioeconomic and ecological metrics. For example, selecting sites based on only socioeconomic metrics captured 16% of the maximum attainable value of functioning mangroves able to provide propagules to potential restoration sites, whereas selecting sites based on ecological and socioeconomic metrics captured 46% of functioning mangroves. Our approach was developed as part of a collaboration between nongovernmental organizations, local government, and academics under rapid delivery time lines given preexisting mangrove restoration implementation commitments. The systematic decision process we used integrated socioeconomic and ecological considerations even under short delivery deadlines, and our approach can be adapted to help mangrove restoration site-selection decisions elsewhere.

Aquatic foods are a vital source of nutrients for coastal communities around the world. The global commitment to expand marine protected areas (MPAs) means it is critical to understand how MPAs affect human nutrition and health. Here, we perform a literature review to identify the major pathways through which sustainable-use MPAs, those that allow for fishing activities within their borders, affect human nutrition and health. We found that sustainable-use MPAs often affect nutrition through three main pathways: (1) changes in fisheries catch, (2) changes in tourism activity, and (3) changes in ancillary programs. We also quantitatively analyze the contribution of sustainable-use MPAs to global catch, revenue, and nutrient supply. We estimate that sustainable-use MPAs contribute an average of 13.6% of global catch, 14% of fisheries revenue, and 13.7% of nutrient supply. Given dire global nutritional vulnerabilities, the potential impacts of MPAs on diets should be a key consideration in MPA expansion discussions.

Monitoring the governance and management effectiveness of area-based conservation has long been recognized as an important foundation for achieving national and global biodiversity goals and enabling adaptive management. However, there are still many barriers that prevent conservation actors, including those affected by governance and management systems from implementing conservation activities and programs and from gathering and using data on governance and management to inform decision-making across spatial scales and through time. We explored current and past efforts to assess governance and management effectiveness and barriers actors face in using the resulting data and insights to inform conservation decision-making. To help overcome these barriers, we developed Elinor, a free and open-source monitoring tool that builds on the work of Nobel Prize winner Elinor Ostrom to facilitate the gathering, storing, sharing, analyzing, and use of data on environmental governance and management across spatial scales and for areas under different governance and management types. We consider the process of codesigning and piloting Elinor with conservation scientists and practitioners and the main components of the assessment and online data system. We also consider how Elinor complements existing approaches by addressing governance and management in a single assessment at a high level for different types of area-based conservation, providing flexible options for data collection, and integrating a data system with an assessment that can support data use and sharing across different spatial scales, including global monitoring of the Global Biodiversity Framework. Although challenges will continue, the process of developing Elinor and the tool itself offer tangible solutions to barriers that prevent the systematic collection and use of governance and management data. With broader uptake, Elinor can play a valuable role in enabling more effective, inclusive, and durable area-based conservation.

Global, regional, and national targets have been set to protect and conserve at least 30 % of the ocean by 2030, in recognition of the important benefits of healthy ocean ecosystems, including for human well-being. Many of these targets recognize the importance of the quality, not just quantity, of areas that are included in the 30 %, such as marine protected areas (MPAs). For example, the Convention on Biological Diversity's Global Biodiversity Framework Target 3 calls for areas to be effectively conserved and managed, ecologically representative, well-connected, and equitably governed. Protecting a percent area is not the sole goal - protection must be effective and equitable. To better understand the quality of biodiversity conservation afforded, in addition to the quantity of area protected, we looked at MPAs across 13 studies that used The MPA Guide and related tools to track Stage of Establishment and Level of Protection as measures of expected biodiversity conservation outcomes across diverse locations, scales, and cultural, political, and conservation contexts. We show that standardized assessments of MPA quality can help to (1) evaluate and improve existing MPAs; (2) plan new MPAs; (3) compare the quality of MPA protection across various scales; (4) track MPA quality, including progress towards coverage targets; (5) enable clear communication and collaboration, and (6) inform actions needed to achieve policy targets and their underlying environmental and social goals, among others. We share common opportunities, challenges, and recommendations for tracking MPA quality at various scales, and using these quality assessments to measure progress towards global targets.

Abstract Global forecasts of ecosystem responses to increasing climatic and anthropogenic pressures are needed to inform adaptation planning. However, data of appropriate spatio-temporal resolution are not typically available to parameterise complex processes at the global scale. Forecast uncertainty associated with ‘data-process’ scale incongruities must be quantified and effectively communicated to avoid over-confident decision-making. Here, we used network models to make probabilistic forecasts of the direction of change in mangrove extent globally under the SSP5-8.5 climate emissions scenario by 2040-2060. We forecast that seaward net loss is the most likely outcome in 77% [±37-78%; 95% confidence] of mangrove forest units, while 30% [±15-59%] will experience landward net gain or stability. Parameter uncertainty limited our capacity to make reliable forecasts everywhere, highlighting where current understanding and global datasets are deficient. However, with action to manage or restore, the number of mangrove forest units likely to experience net gain or stability could nearly double.

Restoration is a key component of global and national efforts to combat ecosystem degradation, reduce biodiversity loss, and adapt to climate change, and there is currently an impetus to scale up restoration efforts. However, our ability to track progress toward restoration targets is limited by the lack of consistent and standardized data on objectives, interventions, and outcomes. To address this, a collaboration of conservation practitioners and scientists from around the world have developed the Mangrove Restoration Tracker Tool (MRTT), an application to record and track outcomes from mangrove restoration projects. The MRTT records information across the lifetime of a project, capturing data describing the site background and pre-restoration baseline and the restoration interventions and costs, as well as post-restoration monitoring that incorporates both socioeconomic and ecological factors. The MRTT allows decision makers, practitioners, and site managers to access information that is essential in making informed, evidence-based decisions on restoration interventions to maximize impact and success.

Despite increasing efforts and investment in mangrove conservation, mangrove cover continues to decline globally. The extent to which protected area (PA) management effectively prevents mangrove loss globally across differing management objectives and governance types is not well understood. We combined remote sensing data with PA information to identify the extent and the drivers of mangrove loss across PAs with distinct governance types and protection levels based on categories developed by the International Union for Conservation of Nature (IUCN). Mangrove loss due to storms and erosion was prevalent across all governance types and most IUCN categories. However, the extent of human-driven loss differed across governance types and IUCN categories. Loss was highest in national government PAs. Private, local, shared arrangement, and subnational government agencies had low human-driven mangrove loss. Human-driven loss was highest in PAs with the highest level of restrictions on human activities (IUCN category I) due to mangrove conversion to areas for commodity production (e.g., aquaculture), whereas PAs that allowed sustainable resource use (e.g., category VI) experienced low levels of human-driven mangrove loss. Because category I PAs with high human-driven loss were primarily governed by national government agencies, conservation outcomes in highly PAs might depend not only on the level of restrictions, but also on the governance type. Mangrove loss across different governance types and IUCN categories varied regionally. Specific governance types and IUCN categories thus seemed more effective in preventing mangrove loss in certain regions. Overall, we found that natural drivers contributed to global mangrove loss across all PAs, whereas human-driven mangrove loss was lowest in PAs with subnational- to local-level governance and PAs with few restrictions on human activities.

Marine protected areas (MPAs) are widely used for ocean conservation, yet the relative impacts of various types of MPAs are poorly understood. We estimated impacts on fish biomass from no-take and multiple-use (fished) MPAs, employing a rigorous matched counterfactual design with a global dataset of >14,000 surveys in and around 216 MPAs. Both no-take and multiple-use MPAs generated positive conservation outcomes relative to no protection (58.2% and 12.6% fish biomass increases, respectively), with smaller estimated differences between the two MPA types when controlling for additional confounding factors (8.3% increase). Relative performance depended on context and management: no-take MPAs performed better in areas of high human pressure but similar to multiple-use in remote locations. Multiple-use MPA performance was low in high-pressure areas but improved significantly with better management, producing similar outcomes to no-take MPAs when adequately staffed and appropriate use regulations were applied. For priority conservation areas where no-take restrictions are not possible or ethical, our findings show that a portfolio of well-designed and well-managed multiple-use MPAs represents a viable and potentially equitable pathway to advance local and global conservation.

Mangroves are a unique ecosystem that provide a wealth of ecosystem services, and hence societal goods and benefits for coastal populations. However, mangroves have long been deforested for human uses. This chapter synthesises knowledge on the benefits of mangroves, their historical and current status, the threats they face, and existing and emerging strategies for their conservation and restoration. Global mangrove loss has slowed substantially since the 1970s‐80s, although mangroves are still threatened by a range of anthropogenic and environmental stressors. Multiple conservation approaches exist, with recent interest in the use of carbon credits. Restoration is possible, but ambitious targets face substantial challenges in their implementation. Solving these challenges will make mangroves a conservation success story.

Aquaculture production is projected to surpass wild-capture fisheries as the primary source of aquatic animal protein in the near future. Farmed shrimp—which are amongst the most valuable aquaculture commodities—are raised predominantly in Southeast Asia and Latin America in a variety of production systems, spanning from extensive to intensive farming. Shrimp aquaculture has been widely criticized for causing mangrove forest degradation and loss, leading to calls for more sustainable aquaculture approaches that protect mangroves. Here we examine an approach promoted as more sustainable—integrated mangrove aquaculture (IMA): a type of farming where mangroves are planted in or alongside shrimp ponds. We argue that mangroves within IMA shrimp systems provide biodiversity and ecosystem functions and services that are, at best, compromised, especially when compared to intact mangrove forests. Given the rapid adoption of IMA approaches, including advocacy for uptake from many governments and non-governmental organizations, there is an urgent need to ensure that these and other aquaculture systems do not result in any conversion of intact mangrove ecosystems into aquaculture ponds, and to identify any benefits (or lack thereof) provided by IMA systems. The increasing adoption of IMA may offer false promises for managing trade-offs between increasing aquaculture productivity and mangrove forest conservation.

Mangrove forests support unique biodiversity and provide a suite of ecosystem services (ES) that benefit people. Decades of continual mangrove loss and degradation have necessitated global efforts to protect and restore this important ecosystem. Generating and evaluating asset maps of biodiversity and ES is an important precursor to identifying locations that can deliver conservation outcomes across varying scales, such as maximising the co-occurrence of specific ES. We bring together global datasets on mangrove-affiliated biodiversity, carbon stocks, fish and invertebrate production, and coastal protection to provide insight into potential trade-offs, synergies and opportunities from mangrove conservation. We map opportunities where high ES provision co-occurs with these areas that could be leveraged in conservation planning, and identify potential high-value opportunities for single ES that might otherwise be missed with a biodiversity focus. Hotspots of single ES, co-occurrence of multiple ES, and opportunities to simultaneously leverage biodiversity and ES occurred throughout the world. For example, efforts that focus on conserving or restoring mangroves to store carbon can be targed to deliver multiple ES benefits. Some nations, such as Vietnam, Oman, Ecuador and China, showed consistent (although not necessarily strong) correlations between ES pairs. A lack of clear or consistent spatial trends elsewhere suggests that some nations will likely benefit more from complementarity-based approaches that focus on multiple sites with high provision of different services. Individual sites within these nations, however, such as Laguna de Terminos in Mexico still provide valuable opportunities to leverage co-benefits. Ensuring that an ES focused approach is complemented by strategic spatial planning is a priority, and our analyses provide a precursor towards decisions about where and how to invest.

Globally, marine protected area (MPA) objectives have increasingly shifted from a primary focus on maintaining ecosystems through prohibiting extractive activities, to more equitable approaches that address the needs of both people and nature. This has led to MPAs with a diverse array of fisheries restrictions and recent debate on the type of restrictions that contribute to achieving biodiversity goals. Here we use a global dataset of 172 MPAs (representing 31 nations) alongside nine detailed case study MPAs (from Australia, Belize, Cambodia, Federated States of Micronesia, Fiji, Indonesia, Madagascar, Solomon Islands, and United States of America), including partially protected areas that allow regulated fishing, to illustrate the many diverse pathways that some MPAs have adopted to protect biodiversity and safeguard the rights and well-being of resource-dependent coastal communities. We group MPAs based on their restrictions and explore four key insights emerging from these groupings using our nine case studies: (i) MPAs use highly diverse approaches to regulate fisheries; (ii) partially protected areas can address gaps in regional fisheries management; (iii) devolving resource management rights to communities influences the chosen fisheries restrictions; and (iv) state-governed MPAs can use highly tailored fisheries restrictions to increase equity in access. We find that partially protected MPAs can offer effective and equitable pathways for biodiversity conservation if tailored to local context. Rather than focusing primarily on fully protected areas for achieving new global MPA targets, we recommend countries use a blend of locally-appropriate protection levels – from fully protected areas to partially protected MPAs to achieve positive biodiversity outcomes.