The Morphology of the Fringing Coral Reefs along the East Coast of Mahé, Seychelles

Abstract

Two types of fringing coral reefs are found along the coast of Mahe: windward reefs exposed to the South East Monsoon, on whose slopes buttresses and grooves are well developed, and sheltered reefs protected from this monsoon, on which buttresses and grooves are not found. The sheltered reefs are dissected by a network of deep channels and depressions which originate in one of three ways: the influx of fresh water from streams, the mechanism by which these reefs advance seaward, and as gaps between fringing reefs around adjacent granite islands. Active linear reefs occur seaward of the sheltered reefs. Two submarine terraces can be recognized: one at about -10 m. and the other at around -20 m. These may result from Pleistocene fluctuations in sea level. The different levels and linear reefs in the forereef environment of the sheltered reefs lead to a complex bottom topography which controls the nature and distribution of the associated unconsolidated sediments.