The greatest diversity of marine habitats with a single region as delineated here, is found between Layou and Pointe Grabier. These include Dominica's largest coral reefs (fringing shallow, fringing deep) along the west coast, oligospecific banks of stony corals, extensive seagrass beds, and a variety of rocky (consolidated, uncosolidated) and sandy habitats within and between the habitats mentioned.

A combination of factors lead to this diversity. On the southern end, the largest river of Dominica (Layou) opens into the sea. It brings sediment to build the shelf and contributes to ample spaces for seagrass beds. In the area around Mero sandy bays and rocky deposits offer the right conditions for sea grasses and coral reefs. The shelf surrounding the Grande Savane area is the widest along the west coast that is also well flushed by ocean currents. Shallow illuminated waters provide ideal conditions for coral reef development and growth. The areas north of Grand Savane are in the rain-shadow of Morne Diablotin. This drier region has fewer rivers that flow year round and so despite the narrow shelf, sea grasses and coral communities thrive where settlements and quarries are not close by.

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For each of the following areas, colored dots mark the presence of specific habitats baring sessile epibenthic communities.

The areas/sites are: 1. Layou to Mero (N end); 2. Mero to Salisbury Beach (N end); 3. Salisbury Beach (N end) to Batali; 4. Batali to Anse Bouleau; 5. Anse Bouleau to Colihaut; 6. Colihaut to Pointe Grabier.