Marine Ecoregions of the World

Introduction and overview

Biological diversity varies over geographic space and the field of biogeography describes the form and pattern of this variation. Quite apart from its ecological and evolutionary interest, such biogeographical study has a critical role to play in nature conservation. Efforts to protect the planet's biodiversity require an understanding of how and where species are distributed. By ensuring a good representation of biogeographic units within a system of protected areas we can come close to ensuring that the full spectrum of life on Earth will also be protected.

Biogeographic maps thus lie at the heart of protected areas network planning and coverage assessment, and have been used as a basis for national and regional studies for a number of years. Simple biogeographic analyses have also been undertaken at the global level to assess progress and highlight gaps in the growing coverage of terrestrial protected areas. (The United Nations List of Protected Areas has regularly published such assessments back to 1980 (Chape et al. 2003).)

The marine environment has lagged considerably behind the terrestrial in using such biogeographic tools: since the late 1990s a growing number of national and regional scale classifications have been devised for marine conservation planning, but the lack of a comprehensive global classification is still widely acknowledged. Although broad-scale systems do exist, none provide both a full global coverage and the fine scale spatial subdivisions necessary to drive representative area-based conservation planning..

Recognizing both the global need and the existence of a large number of incomplete global and regional systems two international nature conservation organizations - The Nature Conservancy (TNC) and the World Wildlife Fund (WWF) - invited a number of other organizations to work with them in reviewing the existing classifications and to develop a synthesized product, a system of Marine Ecoregions of the World (MEOW). This is not a new biogeography, but rather a mosaic of existing, recognized spatial units.

The work was conducted by a small Working Group. An early draft was circulated as an information document to all member states of the Convention on Biological Diversity, while the final version on the Marine Ecoregions of the World was published in BioScience in July/August 2007.