Mussismilia harttii, very abundant in most of the reefs, has
corallites in dichotomous groups with separated calyces,
but does not make branches. Mussismilia braziliensis
and Favia leptophylla show the greatest geographical confinement because they occur only along the eastern Brazilian region. Mussismilia hispida has the largest spatial
distribution and is found from the northern to the southern
regions of Brazil. Siderastrea stellata and Favia gravida
are the most common corals in shallow intertidal pools
of the reef tops. The cosmopolitan Porites astreoides,
P. branneri, Agaricia agaricites, A. fragilis, Montastrea
cavernosa, and Madracis decactis are common in Brazilian reefs. The small Scolymia wellsii, Phyllangia americana, Stephanocoenia michelini, Astrangia braziliensis,
A. rathbuni, and Meandrina braziliensis do not contribute
substantially to the construction of the reef structure.
Recently, three other Caribbean species were described
in the Brazilian reefs: Siderastrea radians, S. siderea,
and Scolymia cubensis (Neves et al., 2006, 2008). Besides
these reef corals, two invasive alien coral species,
Tubastrea coccinea and T. tagusensis were recorded on
rocky shores along the coast of the state of Rio de Janeiro
(De Paula and Creed, 2004). These exotic corals probably
arrived in Brazil on a ship’s hull or oil platform in the late
1980s.
Five species of hydrocorals are described on the Brazilian reefs: Millepora alcicornis, an important reef-building
component in Brazil, predominates on the windward borders of the reefs and is found along the entire tropical coast
of Brazil; Millepora braziliensis (Figure 2g), found in the
high energy zone, is more massive, but has flattened
branches in the protected parts of the reefs; Millepora
nitida (Figure 2h) is currently recorded only along the
eastern region of Brazil. Amaral et al. (2008) described
a new milleporid species, Millepora laboreli, in the northern region of Brazil. Aside from the milleporids, a small
hydrocoral, Stylaster roseus, is found in the protected
parts of reefs in the northeast and east. This species forms
small colonies, a few centimeters high, which have a thick
base covered with small pointed branches.
Major reef types
Brazilian reefs comprise two groups of reefs: nearshore
and offshore reefs. Nearshore reefs occur on the inner continental shelf and are either adjacent to the coast or are
a few kilometers from the shoreline (<5 km). The reefs
adjacent to the coast have, at present, part of their reef flats
covered by siliciclastic sand. These reefs include fringing
reefs and shallow bank reefs. The fringing reefs usually
border the shore of the islands up to several kilometers,
developing above the island substrate as a continuous
fringe. This fringe became narrower with the lowering of
the sea level that occurred in the late Holocene and, thus,
shortened the reef distance from the shoreline and partially
buried the back-reef lagoon. The fore-reef depths can vary
from 5 to 10 m. A very shallow lagoon (1–2 m deep) is
common in the back-reef area where small patch reefs
and coral knolls are observed. Meandering channels may
occasionally interrupt the reef crest. The attached banks
also occur adjacent to the beach but are of limited lateral
(alongshore) extent. Generally these bank-type reefs do
not exceed more than 1 km in length. The entire reef flat
is located in the intertidal zone and no lagoon is formed.
Tidal pools are common, generally of a reduced extent,
say 5–10 m in width and usually not exceeding 1 m in
depth. The reef front depth varies from 5 to 10 m and reef
walls are generally abrupt.
Offshore reefs consist of reef structures of variable
dimensions, from a few meters to 20 km, and are located
more than 5 km off the coastline in various water depths.
These reefs do not form a lagoon, and sediment transport
occurs freely on the leeward side of these reefs. The offshore reefs include the following types of reef: coral
knolls, patch and bank reefs, and coral pinnacles. Coral
knolls can attain maximum dimensions and heights of
a few meters, and are usually found at depths of less than
5 m. Patch reefs have lateral dimensions of tens of meters
with the widths and lengths of the reefs being larger than
the heights. The lateral walls may have a high relief of
approximately 5 m. They are sparsely distributed over
wide areas of the Brazilian inner shelf. The isolated bank
reefs are reef structures which have horizontal dimensions
ranging from approximately 50 m to tens of kilometers,
and their heights above the sea floor vary from 10 m (shallow banks) to more than 20 m (deep banks). This reef type
has variable shapes (irregular, circular, elongate, arc-like,
etc.) and is controlled by its substrate or by its position relative to the present day sea level. Elongate reefs developed
on the lines of beachrock - features that are widely distributed along the northeastern and eastern regions of Brazil.
Larger and irregular bank reefs, such as those of the
Abrolhos area which established on the topographic highs
left by the erosion of older reef carbonates, are also
included in this category. Most are flat-topped reefs that
were truncated during low sea level stands, thereby favoring lateral rather than vertical growth. Submerged banks,
a few meters high, are found in depths up to 20 m, and
may be related to erosional phenomena followed by relative sea level oscillations. Distinctive isolated coral pinnacles range in height from 5 to 25 m above the sea floor,
while the diameter of their tops ranges from 5 to 50 m.
These reefs can be of two types: (a) columnar, where the
base is equally as wide as or wider than the top of the reef;
and (b) chapeirão, where the flat top is wider, sometimes
over three times larger than its base. Chapeirão is a term
introduced by Charles F. Hartt in 1870, which alludes to
hats with broad brims. This coral growth form is unique
to Brazilian reefs and consists of isolated narrow pillars
whose tops are expanded laterally, resembling flat mushrooms (Hartt, 1870). Seen from above, these structures
have an almost perfectly rounded shape and are easily
mapped from aerial photographs. Aside from these reefs,
two other types of oceanic reefs are found in Brazil: (a)
shelf edge reefs that grow at the border of the continental
shelf, with widths up to 3 km and a relief of 35 m at depths
BRAZIL, CORAL REEFS
171
corallites in dichotomous groups with separated calyces,
but does not make branches. Mussismilia braziliensis
and Favia leptophylla show the greatest geographical confinement because they occur only along the eastern Brazilian region. Mussismilia hispida has the largest spatial
distribution and is found from the northern to the southern
regions of Brazil. Siderastrea stellata and Favia gravida
are the most common corals in shallow intertidal pools
of the reef tops. The cosmopolitan Porites astreoides,
P. branneri, Agaricia agaricites, A. fragilis, Montastrea
cavernosa, and Madracis decactis are common in Brazilian reefs. The small Scolymia wellsii, Phyllangia americana, Stephanocoenia michelini, Astrangia braziliensis,
A. rathbuni, and Meandrina braziliensis do not contribute
substantially to the construction of the reef structure.
Recently, three other Caribbean species were described
in the Brazilian reefs: Siderastrea radians, S. siderea,
and Scolymia cubensis (Neves et al., 2006, 2008). Besides
these reef corals, two invasive alien coral species,
Tubastrea coccinea and T. tagusensis were recorded on
rocky shores along the coast of the state of Rio de Janeiro
(De Paula and Creed, 2004). These exotic corals probably
arrived in Brazil on a ship’s hull or oil platform in the late
1980s.
Five species of hydrocorals are described on the Brazilian reefs: Millepora alcicornis, an important reef-building
component in Brazil, predominates on the windward borders of the reefs and is found along the entire tropical coast
of Brazil; Millepora braziliensis (Figure 2g), found in the
high energy zone, is more massive, but has flattened
branches in the protected parts of the reefs; Millepora
nitida (Figure 2h) is currently recorded only along the
eastern region of Brazil. Amaral et al. (2008) described
a new milleporid species, Millepora laboreli, in the northern region of Brazil. Aside from the milleporids, a small
hydrocoral, Stylaster roseus, is found in the protected
parts of reefs in the northeast and east. This species forms
small colonies, a few centimeters high, which have a thick
base covered with small pointed branches.
Major reef types
Brazilian reefs comprise two groups of reefs: nearshore
and offshore reefs. Nearshore reefs occur on the inner continental shelf and are either adjacent to the coast or are
a few kilometers from the shoreline (<5 km). The reefs
adjacent to the coast have, at present, part of their reef flats
covered by siliciclastic sand. These reefs include fringing
reefs and shallow bank reefs. The fringing reefs usually
border the shore of the islands up to several kilometers,
developing above the island substrate as a continuous
fringe. This fringe became narrower with the lowering of
the sea level that occurred in the late Holocene and, thus,
shortened the reef distance from the shoreline and partially
buried the back-reef lagoon. The fore-reef depths can vary
from 5 to 10 m. A very shallow lagoon (1–2 m deep) is
common in the back-reef area where small patch reefs
and coral knolls are observed. Meandering channels may
occasionally interrupt the reef crest. The attached banks
also occur adjacent to the beach but are of limited lateral
(alongshore) extent. Generally these bank-type reefs do
not exceed more than 1 km in length. The entire reef flat
is located in the intertidal zone and no lagoon is formed.
Tidal pools are common, generally of a reduced extent,
say 5–10 m in width and usually not exceeding 1 m in
depth. The reef front depth varies from 5 to 10 m and reef
walls are generally abrupt.
Offshore reefs consist of reef structures of variable
dimensions, from a few meters to 20 km, and are located
more than 5 km off the coastline in various water depths.
These reefs do not form a lagoon, and sediment transport
occurs freely on the leeward side of these reefs. The offshore reefs include the following types of reef: coral
knolls, patch and bank reefs, and coral pinnacles. Coral
knolls can attain maximum dimensions and heights of
a few meters, and are usually found at depths of less than
5 m. Patch reefs have lateral dimensions of tens of meters
with the widths and lengths of the reefs being larger than
the heights. The lateral walls may have a high relief of
approximately 5 m. They are sparsely distributed over
wide areas of the Brazilian inner shelf. The isolated bank
reefs are reef structures which have horizontal dimensions
ranging from approximately 50 m to tens of kilometers,
and their heights above the sea floor vary from 10 m (shallow banks) to more than 20 m (deep banks). This reef type
has variable shapes (irregular, circular, elongate, arc-like,
etc.) and is controlled by its substrate or by its position relative to the present day sea level. Elongate reefs developed
on the lines of beachrock - features that are widely distributed along the northeastern and eastern regions of Brazil.
Larger and irregular bank reefs, such as those of the
Abrolhos area which established on the topographic highs
left by the erosion of older reef carbonates, are also
included in this category. Most are flat-topped reefs that
were truncated during low sea level stands, thereby favoring lateral rather than vertical growth. Submerged banks,
a few meters high, are found in depths up to 20 m, and
may be related to erosional phenomena followed by relative sea level oscillations. Distinctive isolated coral pinnacles range in height from 5 to 25 m above the sea floor,
while the diameter of their tops ranges from 5 to 50 m.
These reefs can be of two types: (a) columnar, where the
base is equally as wide as or wider than the top of the reef;
and (b) chapeirão, where the flat top is wider, sometimes
over three times larger than its base. Chapeirão is a term
introduced by Charles F. Hartt in 1870, which alludes to
hats with broad brims. This coral growth form is unique
to Brazilian reefs and consists of isolated narrow pillars
whose tops are expanded laterally, resembling flat mushrooms (Hartt, 1870). Seen from above, these structures
have an almost perfectly rounded shape and are easily
mapped from aerial photographs. Aside from these reefs,
two other types of oceanic reefs are found in Brazil: (a)
shelf edge reefs that grow at the border of the continental
shelf, with widths up to 3 km and a relief of 35 m at depths
BRAZIL, CORAL REEFS
171