ITME - Marine Habitats of Dominica Version 2008

Coral Habitats on Unconsolidated Rocks


The the near-shore waters along the west coast lined by cliffs or steep terrain, are often littered with large rocks.
Large enough that they are not turned by a storm or hurricane, at least not within a few decades or centuries. These rocks provide the stable substrate for corals and other reef organisms. The lack of coral accretion on these structures does however tell a story, and it is that calcareous organisms are chronically killed/removed by the abrasive effects of sediment-laden storm surges, physical damage or removal by fishing practices (fish pots) and coral mining, and the constant work of bioeroders and biocorroders.

Nevertheless, these habitats provide a great variety of marine life for snorkelers and SCUBA divers. Isolated rocks also attract reef fishes, and the rocky "boulder fields" are ideal nurseries for many fish species. The further away they are from rivers or other sources of chronic sediment input, the more diverse the epilithic community tends to be. The abundant presence of the grazing echinod D. antillarum in some areas, also contributes to reduced overgrowth by algae and a greater abundance of sessile animals. These habitats are also easily accessed and fishing pressure has taken its toll, as can be seen in the paucity of certain fishes and larger size classes of most fish species.

Along the west coast, this is the most common coral habitat easily accessible to snorkels. It generally forms a band of up to 30 meters. Depending on the location, sand flats and seagrass beds are found beyond the rocky areas. Along the east coast, the turbulent near-shore waters make for rather barren or oligospecific assemblages and one must go deeper and farther out (SCUBA) to view comparable assemblages.

Not all areas that are characterized by uncosolidated rocky habitats bare rich sessile epibenthic communities. In fact, the vast majority of such near-shore habitats harbor communities dominated by encrusting calcareous red algae or turf algae, and few sponges, corals, polychaetes and tunicates.

SCCS07

 

 
 
Coral assemblages on rocks (west coast).

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