Map of the Month: Rodriques, Cargados Carajos, and Agalega
Map boundaries: 10 to 20 degrees South; 56 to 64 degrees East
Country: Mauritius
Overview
The southern part of the Mascarene Plateau, the largest submerged bank in the world, is covered with seagrass and interspersed with coral reefs. The plateau extends from north to south roughly along the 60th meridian, and is mostly underwater. Mauritius, home of the dodo, and associated islets are on the southern part of this plateau. North from Mauritius are the shallow banks of the Mascarene Plateau, extending for 1000 miles to the north. From south to north, the shallower parts of the plateau are known as Soudan Banks, Cargados Carajos Shoals, Nazareth Banks, and Saya de Malha. Saya de Malha was an island until the last ice age. Its shallowest point is 8 meters deep.
The islands near Mauritius include Round Island, Flat Island, Gabriel Island, Gunner’s Quoin, Pigeon Rock, and Serpent Island. These islands are notable for bird life such as tropicbirds, puffins, and petrels; as well as rare reptiles. Round Island contains the sole relict of the palm savanna vegetation of Mauritius, as well as large numbers of seabirds.
There are about 40 islands of Cargados Carajos, which is a coral atoll atop a volcano. Vegetation is coconuts, bushes, and grass. The islands are noted for seabird nesting and sea turtle nesting.
Rodrigues is a volcanic island in the far southeast of the map located near where the African, Indo-Australian, and Antarctic plates intersect. There are 18 islets near Rodrigues, which are noted for seabird nesting. Large numbers of plant and animal species on Rodrigues have become extinct since 1600, including 100 plants, the Rodrigues solitaire, and Rodrigues parakeet. Feral animals have changed Rodrigues into a savanna with scattered trees. Endemic birds such as the Rodrigues warbler and Rodrigues fody and animals such as the fruit bat still hang on.
About 700 miles to the north of Mauritius are the two Agalega islands. Coconuts are produced by a Mauritian state company, and other vegetation includes palms, mangroves and Terminalia trees.
World Wildlife Fund Terrestrial Ecoregions
Tropical and Subtropical Moist Broadleaf Forests
AT 113, Granitic Seychelles Forests. Found on Agalega Islands. Includes vegetation like palms, tree ferns, orchids, and pitcher plants.
AT 120, Mascarene Forests. Found on Mauritius, Cardgados Carajos Shoals, and Rodrigues. Forests of ebony trees and palm savannas with 38 endemic genera of plants. The day gecko genus, Phelsuma, occurs on the islands. Other rare repties include boas, skinks, and hawksbill turtles.
Marine Ecoregions of the World
Western Indo-Pacific Realm, Western Indian Ocean Province
97. Cargados Carajos/Tromelin Island. Includes the Mascarene Plateau and Agalega Islands.
98. Mascarene Islands. Includes Mauritius and Rodrigues.
Freshwater Ecoregions of the World
Africa and Madagascar Region, Oceanic Islands
585. Seychelles. Found on Agalega Islands.
586. Mascarenes. Found on Mauritius and Rodrigues. Freshwater habitats contain a highly endemic aquatic biota, including species of gobies in swift mountain streams.
Other items of interest:
Rodriguan coffee plant. The Rodriguan coffee plant had been reduced to one protected individual with a fence around it, heavily pruned by curious residents seeking souvenirs. A cutting was sent to Kew Gardens in London, which grew but couldn’t be induced to make a seed. Then, while hormone treatments were underway, the plant in London and the one on Rodrigues simultaneously flowered for the first time in 200 years. (Krulwich, 2006, full story can be found at NPR link below).
Flat Island. A single hill is topped by a lighthouse. On the north side is Pigeon Rock, a large bare rock sea stack. Ecoregion AT 120.
Gunner’s Quoin. A basaltic island encircled by cliffs (BirdLife International, 2008). Ecoregion AT120.
Round Island. Sole relict of palm savanna of Mauritius, large numbers of seabirds.
Serpent Island. Vast colony of seabirds, mainly terns.
References
Abell, Robin and 27 others. 2008. Freshwater Ecoregions of the World: A New Map of Biogeographic Units for Freshwater Biodiversity Conservation. Bioscience 58:403-414.
BirdLife International. 2008. BirdLife’s Online World Bird Database. Accessed 29/12/2008 at http://www.birdlife.org/
Krulwich, Robert. 2006. The Little Coffee Plant That Wouldn’t Die. All Things Considered, March 28, 2006. Accessed December 2008 at http://www.npr.org/templates/story/story.php?storyId=5307047
Olson, David M., et al., 2001. Terrestrial Ecoregions of the World: A New Map of Life on Earth. BioScience 51:933-938.
Spalding, Mark D. and 14 others. 2007. Marine Ecoregions of the World: A Bioregionalization of Coastal and Shelf Areas. Bioscience 57:573-583.
Van Heygen, E. 2004. http://www.phelsumania.com/. Accessed December 2008.