88
Z.M.A.N. Leiio and R.K.P. Kikuchi
cillus are also important constituents of the Abrolhos reefs flora and contribute to the production of fine (mud-size) inter-reef sediments. Abundant (32-79 o/o) calcareous red crustose algae (Lithothaminion, Lithophyllum, Sporolithon, Porolithon; Figueiredo 1997) are among the major
reef-framework builders in Abrolhos and may represent 20 o/o of the internal structure of coastal reefs (Leao 1982). Foliose macroalgae, like Sargassum sp., followed by Padina sanctae-crucis, Dictyota cervicornis, Lobophora variegata and Dictyopteris plagiograma, cover more than 90 o/o of the
surface of Coastal Arc reefs (Amado-Filho et al. 1997). Algae cover decreases on offshore reefs, possibly due to higher herbivore activity ( Coutinho et
al. 1993). Accelerated foliose algal growth may restrain coral development
and put the reef structures at risk, especially if important algae consumers
(herbivore fishes) are overfished and/or if nutrients increase due to organic sewage discharge. Filamentous turf algae (i.e. Sphacelaria tribuloides
and Ceramium spp.; Figueiredo 1997) may overgrow coralline substrates
and cover up to 80 o/o of the Archipelago fringing reef surface, indicating
high herbivore pressure (Coutinho et al. 1993).
6.3.3 Other Biota
Two species of corallimorpharian sea anemones (Discosoma carlgrenic,
D. sanctithomae) grow attached to reef structures and true sea anemones
( Condylactis gigantea, Bellactis ilkalyseae, Alicia mirabilis, Lebrunia
danae, L. coraligens) are abundant. The endemic soft-bodied zoanthid,
Palythoa caribbaeorum, often covers large areas of reef substrate. Sponges,
which bioerode coral skeletons, occur on shallow reefs as do bioeroding
polychaete worms, both acting as sediment producers. Other polychaete
worms, like the common Spirobranchus, construct calcareous tubes protruding from the surface of living corals or feed on coral polyp tissue (i.e.,
Eurithae complanata), thus leaving the coral skeleton exposed to new larval settlement. Also, bioeroding mollusks are reef sediment producers and
the mollusk Cyphoma macumba inhabits colonies of the Brazilian blade
sea fan Phylogorgia dillatata where it feeds on cnidarians (Castro 1994). A
large number of crustaceans hide in reef crevices and lobster fishing is
widespread on reefs outside the limits of the national park. Among the
echinoderms, the abundant herbivorous sea star Oreaster reticulatus and
sea urchins play an important role on the reefs because they open space for
new coral growth.
The Abrolhos Bank is the southernmost area in the Atlantic Ocean inhabited by large permanent populations of coral reef fishes. Most of the 95
species in the coastal region and reefs are related to the Caribbean fish
Z.M.A.N. Leiio and R.K.P. Kikuchi
cillus are also important constituents of the Abrolhos reefs flora and contribute to the production of fine (mud-size) inter-reef sediments. Abundant (32-79 o/o) calcareous red crustose algae (Lithothaminion, Lithophyllum, Sporolithon, Porolithon; Figueiredo 1997) are among the major
reef-framework builders in Abrolhos and may represent 20 o/o of the internal structure of coastal reefs (Leao 1982). Foliose macroalgae, like Sargassum sp., followed by Padina sanctae-crucis, Dictyota cervicornis, Lobophora variegata and Dictyopteris plagiograma, cover more than 90 o/o of the
surface of Coastal Arc reefs (Amado-Filho et al. 1997). Algae cover decreases on offshore reefs, possibly due to higher herbivore activity ( Coutinho et
al. 1993). Accelerated foliose algal growth may restrain coral development
and put the reef structures at risk, especially if important algae consumers
(herbivore fishes) are overfished and/or if nutrients increase due to organic sewage discharge. Filamentous turf algae (i.e. Sphacelaria tribuloides
and Ceramium spp.; Figueiredo 1997) may overgrow coralline substrates
and cover up to 80 o/o of the Archipelago fringing reef surface, indicating
high herbivore pressure (Coutinho et al. 1993).
6.3.3 Other Biota
Two species of corallimorpharian sea anemones (Discosoma carlgrenic,
D. sanctithomae) grow attached to reef structures and true sea anemones
( Condylactis gigantea, Bellactis ilkalyseae, Alicia mirabilis, Lebrunia
danae, L. coraligens) are abundant. The endemic soft-bodied zoanthid,
Palythoa caribbaeorum, often covers large areas of reef substrate. Sponges,
which bioerode coral skeletons, occur on shallow reefs as do bioeroding
polychaete worms, both acting as sediment producers. Other polychaete
worms, like the common Spirobranchus, construct calcareous tubes protruding from the surface of living corals or feed on coral polyp tissue (i.e.,
Eurithae complanata), thus leaving the coral skeleton exposed to new larval settlement. Also, bioeroding mollusks are reef sediment producers and
the mollusk Cyphoma macumba inhabits colonies of the Brazilian blade
sea fan Phylogorgia dillatata where it feeds on cnidarians (Castro 1994). A
large number of crustaceans hide in reef crevices and lobster fishing is
widespread on reefs outside the limits of the national park. Among the
echinoderms, the abundant herbivorous sea star Oreaster reticulatus and
sea urchins play an important role on the reefs because they open space for
new coral growth.
The Abrolhos Bank is the southernmost area in the Atlantic Ocean inhabited by large permanent populations of coral reef fishes. Most of the 95
species in the coastal region and reefs are related to the Caribbean fish