Eastern Caribbean and Atlantic
173
Brazil and West Africa
MAP6f
The
waters of both Brazil and West Africa are
separated from the Caribbean reefs by vast barriers
inimical to reef growth. For the Brazilian reefs these
barriers include the huge river mouths of the Amazon and
Orinoco, as well as the intervening sediment-rich coastline
of the Guyanas. The coastlines of West Africa (and the
intervening Atlantic islands) are separated from the
Caribbean center of diversity by large expanses of open
ocean. For these reasons there is virtually no supply of
larval recruits from the Caribbean either to Brazil or West
Africa. Hence the coral reef organisms found in these two
areas are ecologically isolated.
Brazil
Coral reef growth in Brazil is limited to the northeast and
eastern shores. Most of the northern coastline of Brazil
is dominated by areas of massive riverine input, with
freshwater and sediments dominating the continental shelf
over wide areas to the east of the Amazon. This coastline
is also swept by the west and northward flow of the
northern arm of the South Equatorial Current, and these
factors combine to isolate Brazil from the Caribbean. A
result of this is that Brazil's coral fauna is notable for
having a low species diversity yet a high degree of
endemism. Just 19 species of reef-building coral are
recognized, of which at least six (including all three
species of the genus Mussismilia). and possibly as many
as ten, are found nowhere else. Another interesting feature
of Brazilian coral communities is that there are no
acroporid corals, which are the major shallow water corals
elsewhere in the world.
The westernmost reef systems, in closest proximity to
the Caribbean, are the recently described Manoel Luis
Reefs, lying relatively close to the Amazon river mouth.
These reefs are some 10 kilometers in length and consist
of numerous pinnacles rising from a depth of 25-30 meters
up to the surface waters. Some 16 hermatypic corals have
been recorded, including 12 scleractinian species. These
reefs are still poorly known, but their location, as the
closest reefs to the Caribbean, may be important for any
movements of species between these regions.
There are a few oceanic islands to the northeast of
Brazil. Coral communities of 12 species form dense
structures, but not true reefs, on the islands of Fernando
de Noronha. The nearby Atol das Rocas is a true atoll
some 3.7 kilometers across, encircling a shallow lagoon.
The carbonate deposits, which are some 10 meters
Left: Mussismilia harttii, one of several species endemic to Brazil (photo: JEN Veronl. Right: Madracis decactis ;s a truly
Atlantic species, found in the Caribbean, Brazil and West Africa. In Brazil it typically forms tall grey columns Iphoto:
JEN Veronl.
173
Brazil and West Africa
MAP6f
The
waters of both Brazil and West Africa are
separated from the Caribbean reefs by vast barriers
inimical to reef growth. For the Brazilian reefs these
barriers include the huge river mouths of the Amazon and
Orinoco, as well as the intervening sediment-rich coastline
of the Guyanas. The coastlines of West Africa (and the
intervening Atlantic islands) are separated from the
Caribbean center of diversity by large expanses of open
ocean. For these reasons there is virtually no supply of
larval recruits from the Caribbean either to Brazil or West
Africa. Hence the coral reef organisms found in these two
areas are ecologically isolated.
Brazil
Coral reef growth in Brazil is limited to the northeast and
eastern shores. Most of the northern coastline of Brazil
is dominated by areas of massive riverine input, with
freshwater and sediments dominating the continental shelf
over wide areas to the east of the Amazon. This coastline
is also swept by the west and northward flow of the
northern arm of the South Equatorial Current, and these
factors combine to isolate Brazil from the Caribbean. A
result of this is that Brazil's coral fauna is notable for
having a low species diversity yet a high degree of
endemism. Just 19 species of reef-building coral are
recognized, of which at least six (including all three
species of the genus Mussismilia). and possibly as many
as ten, are found nowhere else. Another interesting feature
of Brazilian coral communities is that there are no
acroporid corals, which are the major shallow water corals
elsewhere in the world.
The westernmost reef systems, in closest proximity to
the Caribbean, are the recently described Manoel Luis
Reefs, lying relatively close to the Amazon river mouth.
These reefs are some 10 kilometers in length and consist
of numerous pinnacles rising from a depth of 25-30 meters
up to the surface waters. Some 16 hermatypic corals have
been recorded, including 12 scleractinian species. These
reefs are still poorly known, but their location, as the
closest reefs to the Caribbean, may be important for any
movements of species between these regions.
There are a few oceanic islands to the northeast of
Brazil. Coral communities of 12 species form dense
structures, but not true reefs, on the islands of Fernando
de Noronha. The nearby Atol das Rocas is a true atoll
some 3.7 kilometers across, encircling a shallow lagoon.
The carbonate deposits, which are some 10 meters
Left: Mussismilia harttii, one of several species endemic to Brazil (photo: JEN Veronl. Right: Madracis decactis ;s a truly
Atlantic species, found in the Caribbean, Brazil and West Africa. In Brazil it typically forms tall grey columns Iphoto:
JEN Veronl.