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Earth’s islands collectively hold the greatest concentration of biodiversity that exists on our planet. Although islands have long served as important models for understanding the ecology and evolution of biodiversity, islands have also been recognized as epicenters of extinction with approximately 75% of all recent bird, reptile, amphibian, and mammal extinctions occurring on islands. Much of the remaining global island diversity is threatened, with up to 85% of remaining reptile, amphibian, and mammal species, along with nearly half of island birds, at risk of extinction today. Similar figures are expected for other taxonomic groups, for which global assessments are currently missing. This biodiversity crisis is particularly notable on tropical oceanic islands, where species evolved in stable and isolated conditions and are especially vulnerable to the fast pace of ongoing environmental change. As extinctions multiply, island ecosystems begin to crumble and further cascades of species extinction will follow. As a result, the human inhabitants who depend on these ecosystems will lose their livelihoods and ways of life. At the same time, because island ecosystems are relatively simple, they also offer an opportunity to understand how to stop this crisis, and to alter the course of our relationship with biodiversity.

This edited volume provides an important summary of over 200 years of biological research on the oceanic islands of the Gulf of Guinea, highlighting the archipelago’s extraordinary endemism across the tree of life. Much of this diversity is still being formally described to science, and the conservation status of most endemic species has not yet been formally assessed. Likewise, our understanding of species natural history, interactions among species, and characteristics of the islands’ diverse ecosystems is still woefully incomplete. Importantly, these gaps in knowledge hinder our ability to halt biodiversity loss on the islands and to secure a thriving future for the islands’ human inhabitants. In support of the United Nations Small Island Developing States commitment to reach sustainable development, the following activities should be a top priority for the oceanic islands of the Gulf of Guinea over the next 10 years:

  • Field surveys and taxonomic research that target specific taxonomic and geographic gaps in knowledge. Key knowledge gaps are discussed in more detail in each of the taxonomic chapters, but we also note that for some branches of the tree of life, the current state of knowledge for the oceanic islands of the Gulf of Guinea is so sparse that we could not provide a chapter and/or checklist for that particular group. This includes algae, lichens, and several groups of terrestrial (e.g., annelids, bees, flies) and aquatic invertebrates (e.g., crustaceans, corals, echinoderms, sponges). For much of the archipelago’s biodiversity, this work will also necessitate a better understanding of regional species diversity and evolutionary relationships. Molecular techniques will continue to prove an invaluable tool for advancing taxonomy and systematics in these lesser known groups.

  • Mobilizing existing natural history collections and their data to democratize knowledge and expedite biodiversity research. Biodiversity surveys over the last two centuries have resulted in extensive natural history collections that document the diversity and distribution of the archipelago’s terrestrial and aquatic ecosystems. Most of these collections are housed in Europe and the USA, and many have not yet been curated, georeferenced, digitized, and made available to the local or global research community. This critical work must continue and take advantage of the growing availability and accessibility of online platforms for collections data.

  • Integrating data from targeted field surveys and existing collections to map species distributions. The distributions of most species in the oceanic islands of the Gulf of Guinea are unknown, which limits our inference of species richness and endemism across the islands’ ecosystems. Existing natural history collections already hold much of this information, and future surveys should be designed to fill conspicuous gaps in knowledge. These spatial data can be combined with maps of current protected areas and estimates of future climate and land-use change to inform sustainable development and conservation planning that centers biodiversity resilience.

  • Promoting the islands as models for ecological studies. Biodiversity is dynamic and relies on complex interactions at multiple levels of organization that are challenging to study. As the species and ecosystems of the Gulf of Guinea oceanic islands become more completely documented, hypothesis-driven studies to promote a deeper understanding of their ecology are becoming possible. Although few such studies have been conducted, it is already clear that the islands are valuable mesocosms to test and develop advanced ecological theories, including population dynamics, community ecology, species interactions, ecosystem resilience, and the impact of human activities on biodiversity.

  • Bolstering local taxonomic expertise and resources for biological research. An increasing number of Santomean and Equatoguinean researchers are contributing to biodiversity science, but this community is still small and largely under resourced. Local institutions, including universities, herbaria, botanical gardens, and libraries, need an influx of funding and training to support the growth in taxonomic expertise and leadership that is essential for islanders to direct the next phase of biodiversity research and environmental stewardship.

  • Augmenting resources for island residents of all ages to learn about their local biodiversity. Effective biodiversity conservation requires a well-informed and engaged local community. Currently, science literacy in the Gulf of Guinea oceanic islands is limited and formal curricula do not feature the islands’ unique biological heritage. Developing widely available, accessible references and environmental learning opportunities for those with less scientific training will be vital to stimulate environmental stewardship and to recruit more local naturalists. These resources can also serve to advertise the islands as a destination for sustainable tourism. The contents of this book can serve as a baseline reference for updating school and university science curricula to focus on local biodiversity, ecosystems, and environmental stewardship. Likewise, this book can serve as a reference for developing taxon-focused field guides with illustrations, distribution maps, natural history accounts, identification keys, and interactive tools. Finally, featuring local biodiversity in community spaces through art, music, and theatrical performances can further extend the reach of biodiversity knowledge and stewardship.

The next 10 years will be critical to set the stage for biodiversity conservation and sustainable development in the oceanic islands of the Gulf of Guinea. Building on a foundation of more than two centuries of biodiversity science, robust commitments from local leadership, and strong cross-sector partnerships, this unique archipelago is well situated to change course from cascades of species extinction towards a thriving future for biodiversity. Most powerfully of all, the islands can teach us how to assess and support healthy ecosystem function and scale these approaches to Earth’s larger systems.