The Sea Around Us Estuaries Database

Jacqueline Alder

When most people try to visualize ‘The Sea’, they envisage large expanses of surface waters, and perhaps the underlying ecosystems. Yet, the sea also includes the coast – where the land meets the sea, and where one finds some of the world’s most productive marine areas, such as coral reefs, seagrass beds and mangroves. Coastal areas are of great importance to fisheries, not to mention tourism, aquaculture, transportation, and oil and gas. This is particularly important as the Sea Around Us covers low latitude areas, i.e., the Caribbean, West Africa and the tropical Indo-Pacific, where large numbers of fishers depend on coastal resources.

Dealing explicitly with coastal areas opens up a wealth of research opportunities, e.g., quantifying the relationships between estuaries and shrimps; re-evaluating the ecosystem services of various coastal habitats; linking marine protected area habitats with communities and small-scale fishers with coastal habitats; and assessing river-basin impacts on coastal systems. As a contribution to such efforts, the Sea Around Us developed a preliminary global database of estuaries, all linked to the over 16,000 ‘coastal’ ½ x ½ degree latitude/longitude cells used for all spatial features by the Sea Around Us.

Specifically, this database, the first to be designed at a global scale, contains over 1,200 estuaries (including some lagoon systems and fjords), in over 120 countries and territories (Alder 2003). These water bodies (of which over 95% have shape files) were selected such that the estuaries of all the world major rivers were included, as well as the small estuaries of countries without major rivers. Overall, the database accounts for over 80% of the world’s freshwater discharge, and contains information about the name, location, area (in km2) and mean freshwater discharge (in m3·s-1), calculated over a specified number of years. Where available, shape files were used to identify the ‘estuarine cells’ among the ½ degree coastal cells in our global ocean cell system. The estuarine cells (or more precisely: coastal cells with a given fraction of their area overlapping with one or several estuaries) were subsequently used to refine the distributions of fishes and invertebrates with estuarine affinities.

Currently, our database is also available and viewable via the UNEP-WCMC Ocean Data Viewer at


Alder J (2003) Putting the Coast in the Sea Around Us Project. The Sea Around Us Newsletter No. 15:1-2.