WORLD ATLAS OF SEAGRASSES A patch reef in the Philippines surrounded by a luxuriant mixed bed of Thalassia hemprichii and Syringodium isoetmium. seagrass distribution, and seagrass functions and threats at a global level. Later, additional chapter authors were asked to contribute to represent regions of the world not yet well covered; also, chapter authors invited co-authors to join their effort. The geographical coverage of the World Atlas reflects this process. The second section of the World Atlas of Seagrasses consists of 24 regional and national chapters. In each chapter, the authors have synthesized knowledge of seagrasses, the plants' biogeography, ecology and associated species, historical perspectives and threats to the ecosystem as well as management policies pertaining to seagrasses. Wherever possible, the authors have estimated the area of seagrass in their region and summarized its status. Case studies throughout the chapters highlight particularly interesting seagrass habitats and areas where human or natural impacts to seagrasses are of concern. order to achieve the visibility and recognition necessary to protect this valuable global resource. Public perception translates into political interest. Perceptions of seagrass ecosystems must achieve comparable status with those of coral reef and mangrove ecosystems, through the creation of global maps, global estimates of loss, knowledge of human impacts to the ecosystem, regular monitoring of ecosystem status and a global plan of action to reverse seagrass ecosystem decline. It is our hope that the World Atlas of Seagrasses will contribute to the more widespread recognition, understanding, and protection of seagrass ecosystems worldwide. ORGANIZATION OF THIS WORLD ATLAS The World Atlas of Seagrasses is presented in two sections. The first section comprises a Global Overview of the state of our knowledge of seagrasses. It presents detailed ecosystem distribution and species diversity maps and the most accurate possible estimate of global seagrass area. Appendices supply seagrass species lists for almost 180 countries and territories, a list of marine protected areas known to include seagrasses and a collection of species range maps. The Global Overview was based on a compilation of seagrass literature and a workshop held in Florida with seagrass scientists from around the world contributing their regional knowledge and expertise. The Global Seagrass Workshop, sponsored by UNEP-WCMC, with considerable assistance from the World Seagrass Association, was held in St Petersburg, Florida in November 2001 specifically to begin assembling information on global seagrass distribution for the World Atlas See page 2871. Twenty-three delegates from 1 5 countries participated, and all are represented here as chapter authors. The workshop was a forum for discussion on the organization of an atlas, regional Dugong feeding on Halophila ovatis, Vanuatu, western Pacific islands. Of course, any comprehensive atlas builds on the work of many scientists beyond the chapter authors. Seagrass science owes much to den Hartog's Seagrasses of the World and the many subsequent publications and books that are referenced throughout the World Atlas. All of the references used to compile the World Seagrass Distribution Map (reproduced on page 21), as well as the individual chapter references, appear in an online bibliography at httpwww. unep-wcmcorgmarineseagrassatlasreferences.