CORDIO East Africa

Living within planetary limits requires attention to justice as biophysical boundaries are not inherently just. Through collaboration between natural and social scientists, the Earth Commission defines and operationalizes Earth system justice to ensure that boundaries reduce harm, increase well-being, and reflect substantive and procedural justice. Such stringent boundaries may also affect ‘just access’ to food, water, energy and infrastructure. We show how boundaries may need to be adjusted to reduce harm and increase access, and challenge inequality to ensure a safe and just future for people, other species and the planet. Earth system justice may enable living justly within boundaries. Biophysical boundaries are not inherently just. A collaboration between social and natural scientists, the Earth Commission, defines and operationalizes Earth system justice to ensure that biophysical boundaries reduce harm, increase well-being, and reflect substantive and procedural justice.

Over the last two decades, coral reefs have experienced dire declines due to intensifying anthropogenic disturbances and climate change. Defining and quantifying coral reef resilience now represents a critical management objective, but there is still little consensus on the approach and the indices to be used. In this study, we develop a multi-factor reef recovery index based on the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method to assess the vulnerability of several insular coral reefs in the South Western Indian Ocean (SWIO) from 2016 to 2018. We showed, that in the wake of a regional bleaching event in 2016, the most isolated reefs of Europa, which is characterized by low direct human impact had the highest recovery potential. On the contrary, islands that are more prone to direct human influence (i.e., La Reunion and Rodrigues) displayed the lowest recovery potential.

Despite decades of increasing investment in conservation, we have not succeeded in ''bending the curve'' of biodiversity decline. Efforts to meet new targets and goals for the next three decades risk repeating this outcome due to three factors: neglect of increasing drivers of decline; unrealistic expectations and time frames of biodiversity recovery; and insufficient attention to justice within and between generations and across countries. Our Earth system justice approach identifies six sets of actions that when tackled simultaneously address these failings: (1) reduce and reverse direct and indirect drivers causing decline; (2) halt and reverse biodiversity loss; (3) restore and regenerate biodiversity to a safe state; (4) raise minimum wellbeing for all; (5) eliminate over-consumption and excesses associated with accumulation of capital; and (6) uphold and respect the rights and responsibilities of all communities, present and future. Current conservation campaigns primarily address actions 2 and 3, with urgent upscaling of actions 1, 4, 5, and 6 needed to help deliver the post-2020 global biodiversity framework.

We review the current knowledge of the biodiversity of the ocean as well as the levels of decline and threat for species and habitats. The lack of understanding of the distribution of life in the ocean is identified as a significant barrier to restoring its biodiversity and health. We explore why the science of taxonomy has failed to deliver knowledge of what species are present in the ocean, how they are distributed and how they are responding to global and regional to local anthropogenic pressures. This failure prevents nations from meeting their international commitments to conserve marine biodiversity with the results that investment in taxonomy has declined in many countries. We explore a range of new technologies and approaches for discovery of marine species and their detection and monitoring. These include: imaging methods, molecular approaches, active and passive acoustics, the use of interconnected databases and citizen science. Whilst no one method is suitable for discovering or detecting all groups of organisms many are complementary and have been combined to give a more complete picture of biodiversity in marine ecosystems. We conclude that integrated approaches represent the best way forwards for accelerating species discovery, description and biodiversity assessment. Examples of integrated taxonomic approaches are identified from terrestrial ecosystems. Such integrated taxonomic approaches require the adoption of cybertaxonomy approaches and will be boosted by new autonomous sampling platforms and development of machine-speed exchange of digital information between databases.

Deep reefs below 30 m provide essential ecosystem services for ocean health and human well-being such as food security and climate change resilience. Yet, deep reefs remain poorly researched and largely unprotected, including in the Western Indian Ocean (WIO). Here, we assessed current conservation approaches in the WIO focusing on deep reefs, using a combination of online surveys and semi-structured interviews. Results indicated that deep-reef data are sparse and commonly stemming from non-peer-reviewed or non-publicly available sources, This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. 2 of 11 STEFANOUDIS et al. and are often not used to inform conservation of WIO marine protected areas. Based on those findings, we co-developed a framework with WIO stakehold-ers comprising recommendations linked to specific actions to be undertaken by regional actors to improve the capacity of the region to collect and share deep-reef information. We hope this framework will enhance deep-reef stewardship and management throughout the WIO and thus aid sustainable blue economic growth in the region.

Governments are negotiating actions intended to halt biodiversity loss and put it on a path to recovery by 2050. Here, we show that bending the curve for biodiversity is possible, but only if actions are implemented urgently and in an integrated manner. Connecting these actions to biodiversity outcomes and tracking progress remain a challenge.

Ocean warming is increasing the incidence, scale, and severity of global-scale coral bleaching and mortality, culminating in the third global coral bleaching event that occurred during record marine heatwaves of 2014-2017. While local effects of these events have been widely reported, the global implications remain unknown. Analysis of 15,066 reef surveys during 2014-2017 revealed that 80% of surveyed reefs experienced significant coral bleaching and 35% experienced significant coral mortality. The global extent of significant coral bleaching and mortality was assessed by extrapolating results from reef surveys using comprehensive remote-sensing data of regional heat stress. This model predicted that 51% of the world’s coral reefs suffered significant bleaching and 15% significant mortality, surpassing damage from any prior global bleaching event. These observations demonstrate that global warming’s widespread damage to coral reefs is accelerating and underscores the threat anthropogenic climate change poses for the irreversible transformation of these essential ecosystems.

The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO and adjacent waters (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endangered, five are Endangered, and seven are Vulnerable. A further seven (10%) are Near Threatened, 33 (47.1%) are Least Concern, and 17 (24.2%) are Data Deficient. While the primary threat is overfishing, there are the first signs that climate change is contributing to elevated extinction risk through habitat reduction and inshore distributional shifts. By backcasting their status, few species were threatened in 1980, but this changed soon after the emergence of targeted shark and ray fisheries. South Africa has the highest national conservation responsibility, followed by Mozambique and Madagascar. Yet, while fisheries management and enforcement have improved in South Africa over recent decades, drastic improvements are urgently needed elsewhere. To avoid extinction and ensure robust populations of the region’s endemic sharks and rays and maintain ecosystem functionality, there is an urgent need for the strict protection of Critically Endangered and Endangered species and sustainable management of Vulnerable, Near Threatened, and Least Concern species, underpinned by species-level data collection and reduction of incidental catch.

Ecosystems worldwide are under increasing threat. We applied a standardized method for assessing the risk of ecosystem collapse, the International Union for Conservation of Nature (IUCN) Red List of Ecosystems, to coral reefs in the Western Indian Ocean (WIO), covering 11,919 km² of reef (~5% of the global total). Our approach combined indicators of change in historic ecosystem extent, ecosystem functioning (hard corals, fleshy algae, herbivores and piscivores) and projected sea temperature warming. We show that WIO coral reefs are vulnerable to collapse at the regional level, while in 11 nested ecoregions they range from critically endangered (islands, driven by future warming) to vulnerable (continental coast and northern Seychelles, driven principally by fishing pressure). Responses to avoid coral reef collapse must include ecosystem-based management of reefs and adjacent systems combined with mitigating and adapting to climate change. Our approach can be replicated across coral reefs globally to help countries and other actors meet conservation and sustainability targets set under multiple global conventions—including the Convention on Biological Diversity’s post-2020 global biodiversity framework and the United Nations’ Sustainable Development Goals.

Communities of coral reef fishes are changing due to global warming and overfishing. To understand these changes and inform conservation, knowledge of species diversity and distributions is needed. The western Indian Ocean (WIO) contains the second highest coral reef biodiversity hotspot globally, yet a detailed analysis of the diversity of coral reef fishes is lacking. This study developed a timed visual census method and recorded 356 species from 19 families across four countries in the WIO to examine patterns in species diversity. Species richness and composition differed most between the island countries of Madagascar and Comoros and both these locations differed from locations in Tanzania and Mozambique which were similar. These three regional groupings helped define WIO ecoregions for conservation planning. The highest species richness was found in Tanzania and Mozambique, and the lowest and most different species composition was found in Comoros. Biogeography explains these differences with naturally lower species diversity expected from the small, oceanic, and isolated islands of Comoros. Present day ocean currents maintain these diversity patterns and help explain the species composition in northeast Madagascar. Species distributions were driven by 46 of the 356 species; these provide guidance on important species for ongoing monitoring. The results provide a benchmark for testing future changes in reef fish species richness.

Programs and initiatives aiming to protect biodiversity and ecosystems have increased over the last decades in response to their decline. Most of these are based on monitoring data to quantitatively describe trends in biodiversity and ecosystems. The estimation of such trends, at large scales, requires the integration of numerous data from multiple monitoring sites. However, due to the high heterogeneity of data formats and the resulting lack of interoperability, the data integration remains sparsely used and synthetic analyses are often limited to a restricted part of the data available. Here we propose a workflow, comprising four main steps, from data gathering to quality control, to better integrate ecological monitoring data and to create a synthetic dataset that will make it possible to analyse larger sets of monitoring data, including unpublished data. The workflow was designed and applied in the production of the Status of Coral Reefs of the World: 2020 report, where more than two hundred individual datasets were integrated to assess the status and trends of hard coral cover at the global scale. The workflow was applied to two case studies and associated R codes, based on the experience acquired during the production of this report. The proposed workflow allows for the integration of datasets with different levels of taxonomic and spatial precision, with a high degree of reproducibility. It provides a conceptual and technical framework for the integration of ecological monitoring data, allowing for the estimation of temporal trends in biodiversity and ecosystems or to test ecological hypotheses at larger scales.

Maintaining healthy, productive ecosystems in the face of pervasive and accelerating human impacts including climate change requires globally coordinated and sustained observations of marine biodiversity. Global coordination is predicated on an understanding of the scope and capacity of existing monitoring programs, and the extent to which they use standardized, interoperable practices for data management. Global coordination also requires identification of gaps in spatial and ecosystem coverage, and how these gaps correspond to management priorities and information needs. We undertook such an assessment by conducting an audit and gap analysis from global databases and structured surveys of experts. Of 371 survey respondents, 203 active, long-term (>5 years) observing programs systematically sampled marine life. These programs spanned about 7% of the ocean surface area, mostly concentrated in coastal regions of the United States, Canada, Europe, and Australia. Seagrasses, mangroves, hard corals, and macroalgae were sampled in 6% of the entire global coastal zone. Two-thirds of all observing programs offered accessible data, but methods and conditions for access were highly variable. Our assessment indicates that the global observing system is largely uncoordinated which results in a failure to deliver critical information required for informed decision-making such as, status and trends, for the conservation and sustainability of marine ecosystems and provision of ecosystem services. Based on our study, we suggest four key steps that can increase the sustainability, connectivity and spatial coverage of biological Essential Ocean Variables in the global ocean: (1) sustaining existing observing programs and encouraging coordination among these; (2) continuing to strive for data strategies that follow FAIR principles (findable, accessible, interoperable, and reusable); (3) utilizing existing ocean observing platforms and enhancing support to expand observing along coasts of developing countries, in deep ocean basins, and near the poles; and (4) targeting capacity building efforts. Following these suggestions could help create a coordinated marine biodiversity observing system enabling ecological forecasting and better planning for a sustainable use of ocean resources.

The southwest Indian Ocean (SWIO) is a hotspot of endemic and evolutionarily distinct sharks and rays. We summarise the extinction risk of the sharks and rays endemic to coastal, shelf, and slope waters of the SWIO and adjacent waters (Namibia to Kenya, including SWIO islands). Thirteen of 70 species (19%) are threatened: one is Critically Endangered, five are Endangered, and seven are Vulnerable. A further seven (10%) are Near Threatened, 33 (47.1%) are Least Concern, and 17 (24.2%) are Data Deficient. While the primary threat is overfishing, there are the first signs that climate change is contributing to elevated extinction risk through habitat reduction and inshore distributional shifts. By backcasting their status, few species were threatened in 1980, but this changed soon after the emergence of targeted shark and ray fisheries. South Africa has the highest national conservation responsibility, followed by Mozambique and Madagascar. Yet, while fisheries management and enforcement have improved in South Africa over recent decades, drastic improvements are urgently needed elsewhere. To avoid extinction and ensure robust populations of the region’s endemic sharks and rays and maintain ecosystem functionality, there is an urgent need for the strict protection of Critically Endangered and Endangered species and sustainable management of Vulnerable, Near Threatened, and Least Concern species, underpinned by species-level data collection and reduction of incidental catch.

Understanding how Marine Protected Areas (MPAs) improve conservation outcomes across anthropogenic pressures can improve the benefits derived from them. Effects of protection for coral reefs in the western and central Indian Ocean were assessed using size-spectra analysis of fish and the relationships of trophic group biomass with human population density. Length-spectra relationships quantifying the relative abundance of small and large fish (slope) and overall productivity of the system (intercept) showed inconsistent patterns with MPA protection. The results suggest that both the slopes and intercepts were significantly higher in highly and well-protected MPAs. This indicates that effective MPAs are more productive and support higher abundances of smaller fish, relative to moderately protected MPAs. Trophic group biomass spanning piscivores and herbivores, decreased with increasing human density implying restoration of fish functional structure is needed. This would require addressing fisher needs and supporting effective MPA management to secure ecosystem benefits for coastal communities.

Plain Language Summary Mass bleaching events caused by warming oceans and intensifying marine heatwaves have killed millions of corals globally. In the central equatorial Pacific, coral reefs experienced three extreme heatwaves within 15 years, providing valuable insights into the mechanisms that could facilitate coral survival under global warming. We examined an 18‐year record of coral cover in the Phoenix Islands Protected Area (PIPA) to track the community response to each event. In the 2002/2003 heatwave, coral communities across PIPA were decimated, with some reefs experiencing near complete mortality. Strong recovery followed and in 2009/2010, a heatwave of similar magnitude caused minimal mortality. The 2015/2016 heatwave was the strongest on record, exposing PIPA's coral communities to twice the thermal stress of 2002/2003. Yet coral mortality during this event was disproportionately low. An examination of 11 environmental metrics that may have modulated the impacts of extreme heat revealed no consistent explanation. Rather, our results support the hypothesis that the survival of thermally tolerant colonies in 2002/2003 and localized recruitment, facilitated recovered communities with greater thermal tolerance than those that inhabited the reefs two decades ago. Understanding and promoting the conditions that facilitate coral recovery and adaptation would enhance our ability to foster coral reef survival.

Despite substantial conservation efforts, the loss of ecosystems continues globally, along with related declines in species and nature’s contributions to people. An effective ecosystem goal, supported by clear milestones, targets and indicators, is urgently needed for the post-2020 global biodiversity framework and beyond to support biodiversity conservation, the UN Sustainable Development Goals and efforts to abate climate change. Here, we describe the scientific foundations for an ecosystem goal and milestones, founded on a theory of change, and review available indicators to measure progress. An ecosystem goal should include three core components: area, integrity and risk of collapse. Targets—the actions that are necessary for the goals to be met—should address the pathways to ecosystem loss and recovery, including safeguarding remnants of threatened ecosystems, restoring their area and integrity to reduce risk of collapse and retaining intact areas. Multiple indicators are needed to capture the different dimensions of ecosystem area, integrity and risk of collapse across all ecosystem types, and should be selected for their fitness for purpose and relevance to goal components. Science-based goals, supported by well-formulated action targets and fit-for-purpose indicators, will provide the best foundation for reversing biodiversity loss and sustaining human well-being.