The northern portion of the west coast is also quite diverse in it's array of habitats. Although true reefs are only present in the form of isolated patch reefs, healthy coral communities are found off the cliffs of Morne Espagnol and the western half of the Cabrits where they grow on extensive rocky habitats (boulder fields).

The band of seagrasses which can be followed from the Layou River almost seamlessly is interrupted near the Espagnol River. It continues on the southern end of Pointe Ronde although in a much sparser and patchier distribution. Throughout Prince Rupert's Bay. Seagrasses are patchy and include numerous areas with invasive species. Similarity, patch reefs in this area are for the most part dead.

The southern shore of the Cabrits harbors remnants of patch reefs that were probably mined during the construction of Fort Shirley. The patch reefs along the northern end of the Cabrits also show signs of sever physical destruction. Within the swampy area east of Cabrits, white mangroves can be found.

A fairly solid band of seagrasses starts on the southern end of Douglas Bay and continues all the way to Anse Bell. In that stretch coral assemblages on rocks in Douglas Bay (N), the patch reefs of Toucari Bay (s) and the coral assemblages on large consolidated rock formations near the Hermitage River can also be found.

For each of the following areas /sites, colored dots (see key below map) mark the presence of specific habitats baring sessile epibenthic communities.

The areas/sites are: 1. Pointe Crabier to Bioche; 2. Bioche to Espagnol River; 3. Espagnol River to Ti Bai; 4. Ti Bai to Lamoins River; 5. Lamoins River to Indian River; 6. Indian River to Swamp Ravine (work in progress); 7. the Cabrits or Swamp Ravine to Bell Hall River; 8. Bell Hall River to Manicu River (Tanetane); 9. Manicu River to Toucari Bay (N); 10. Toucari Bay to Anse Bell; 11. Anse Bell to Capucin.

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.

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.

The southern region of the west coast is the most populated and in parts possibly the most altered by humans. Alterations include restricting the Roseau River to a single outflow in the 18th century and more recently the construction of various sae-defense walls protecting coastal roads. Population centers are in close proximity of the narrow shelf and its marine resources.

South of Roseau the young volcanic peaks shape the underwater world by being the source of the rocky outcrops and sublittoral environments on which epibenthic organism can settle. Reef coral assemblages and a few patch reefs line the stable substrates. Extreme topographic scenarios include vertical walls of which only the upper portions are settled by light dependent organisms. The invasive coral Tubastraea coccinea has so far been identified at two locations within area 2 (see below). Where rivers deposit sediments (e.g. Pt. Michel) seagrassses (Syringodium) are well established. Mixed stands of Thalassia and Syringodium were present at Cachacrou prior to Hurricane Dean (Aug 2007). In November 2007 only a few patches of Halophila and individual shoots of Syringodium were at this location.

North of Roseau the shelf widens slightly and broadens the spectrum of habitat types. In Fond Cole a variety of coral habitats are established on consolidated and unconsolidated rocks. This area also includes some of the oldest corals of Dominica estimated to be over 500 years old. Seagrasses are well developed all the way to Layou. To date, the Canefield cliffs are the southernmost distribution point identified for the invasive Halophila stipulaceae.

For each of the following areas, colored dots (see key below map) mark the presence of specific habitats baring sessile epibenthic communities.

The area/sites are: 1. Scott's Head to Soufriere; 2. Soufriere to Champagne; 3. Champagne to Pointe Michel (cemetery); 4. Pointe Michel to Newtown (S) (work in progress); 5. Newtown (S) to Roseau (River)(work in progress); 6. Roseau to Fond Cole (work in progress); 7 Fond Cole to Canefield (River); 8. Canefield to Les Pointes (N); 9. Les Pointes to Tarou Point (Rodney's Rock); 10. Tarou Point to Layou River.