Graph showing the amount of substrate available to shallow life in the Chagos archipelago.  Huge amounts exist  (many hundreds of square km) especially between 15 and 40 m deep, and again at 70-90 m deep.  The shallower peak is well within the zone with most diversity and cover.  Despite the small size of the atolls, the archipelago provides a very large and important quantitiy of habitat for reef species.  (Top line is all recorded substrate; bottom line is the main atolls, including the Great Bank, only.  Data obtained from digitising the several thousand depth readings from all available charts of the area, and computation in a GIS.)
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