Ecosystem Data: A Global Map of Human Impact on Marine Ecosystems, 2008

What happens in the vast stretches of the world's oceans - both wondrous and worrisome - has too often been out of sight, out of mind. The sea represents the last major scientific frontier on planet earth - a place where expeditions continue to discover not only new species, but even new phyla. The role of these species in the ecosystem, where they sit in the tree of life, and how they respond to environmental changes really do constitute mysteries of the deep. Despite technological advances that now allow people to access, exploit or affect nearly all parts of the ocean, we still understand very little of the ocean's biodiversity and how it is changing under our influence. The goal of the research presented here is to estimate and visualize, for the first time, the global impact humans are having on the ocean's ecosystems. Our analysis, published in Science, February 15, 2008 (http://doi.org/10.1126/science.1149345), shows that over 40% of the world's oceans are heavily affected by human activities and few if any areas remain untouched. Global data for marine ecosystems are largely non-existent; here we used available data for several ecosystems, modeled the distribution of many other ecosystems, and assumed a uniform distribution for several intertidal ecosystems for which no data exist. We recognize that differences exist in how people classify ecosystems; for example, estuaries are often considered an ecosystem, but here we focus on the ecosystems (also often labeled ‘habitats’) that occur within estuaries (salt marsh, intertidal mud, beach, soft sediment, mangroves, etc.). All ecosystem data were represented at 1 km2 resolution. This dataset contains maps for 20 distinct marine ecosystems used in the impacts model. More information on data sources can be found in the methods section.