Distribution and size of benthic marine habitats in Dominica, Lesser Antilles

Surveys of benthic marine habitats encompassing 1814.7 ha and lining 90% of Dominica's shoreline were carried out to build the first composite picture of the distribution and size of the island's near-shore sublittoral habitats, and the epibenthic communities they harbor. Field survey sites covered areas ranging from 1425 to 29.6 ha, lining the shore in bands ranging between 50 and 250 m in width, in waters no deeper than 30 m. Thus a total of 755 ha of benthos were surveyed in October and November of 2007. The benthic habitat composition of an additional 1059.7 ha was inferred with the help of unpublished data and satellite imagery. Seagrass beds were the most widespread organism-built habitat type with 265 ha. Coral reefs covered 72.2 ha. Both of these habitats were predominantly established along the West and North coasts, which included the island's most habitat-diverse regions. Rocky environments (911.5 ha) dominated the East and South coast and together with sandy areas (566 ha) constituted 81% of the island's marine benthos. It is apparent that seagrass beds, which include four native and one invasive seagrass species, had not been surveyed as previous distribution reports could not be confirmed. Similarly, the benthic cover of Dominica's coral reefs is evidently far below the previously reported 7000 ha. Such discrepancies highlight the advantage of environmental assessments based on field surveys and systematic data compilation, particularly in cases like Dominica where a narrow island shelf stages marginal marine resources in spatial proximity to each other and human settlements. This study has demonstrated how low-tech field methods can be applied on an island-wide scale to build an inventory of marine resources in the form of habitat maps and data repositories publicly accessible for future use. In the absence of such efforts, the development of conservation measures and status reports will remain ill founded.