Communities Structure of Reef Corals
279
differed from the above-considered on the Pacific reefs by the relative
abundance of gorgonians. Most common among them were Rabdoplexaura,
Plexauroides, Echinogorgia, Acabaria, Mopsella, and Bebryce. The hard
octocorals Heliopora were numerous on flat shallows. This coral is common
on many reefs of the Indo-Pacific. Often it forms the micro atolls on submerged reef flats (Zann and Bolton 1985).
The above data show that in communities of octocorals on reefs of the
Indo-Pacific the aIcyonaceans most often largely dominate over the gorgonaceans. Only on reefs off the Vietnamese coasts were gorgonaceans
dominating, because of their ability better to withstand siltation, drops in
temperature and salinity during the winter monsoons peculiar to this area.
In contrast, on the reefs of the western Atlantic gorgonaceans absolutely
predominate over aIcyonaceans. Moreover, they are often a leading component of the sessile bottom fauna (Bayer 1961; Goldberg 1973; Opresko 1973;
Kinzie 1973; Preston and Preston 1975; Muzik 1982; Lasker and Coffroth
1983; Yoshioka and Yoshioka 1989). The number of colonies of gorgonians
reaches on many reefs 20-40m- 2 and the biomass over 0.5 kgm- 2 . Shannon's
index of species diversity (H') in octo coral communities often approaches
that of scleractinians: 1.5-33. Its maximum values they attain in upper
zones of the outward reef slope. The total number of species of octocorals in
coral communities of the western Atlantic varies between 16 on the Puerto
Rican reefs and 47 on reefs of Florida, which is close to that of scleractinians.
Most common reef gorgonians on reefs of this region belong to the two
families, Plexauridae and Gorgoniidae. Among them there are also several
species from the family. Paramuricidae (genus Swiftia) Elisellidae, and
the scleraxonian gorgonians Briareum, Erythropodium and Icilligorgia.
Among the plexaurid gorgonians the most common are Plexaura flexuosa,
P. homomalla, Plexaurella dichotoma, P. grisea, P. fusifera, Eunicea calyculata, E. asperula, E. tourneporti, E. pinta, E. succinea, Pseudoplexaura
circus, P. porosa, P. flagellosa, Muricea muricata, M. atlantica, Muriceopsis
potula, and M. flavida. The most common eugorgonians are Pseudopterogorgia americana, P. bipinnata, P. rigida, P. callos, P. elisabethae, P. acerosa,
Pterogorgia citrina, P. ancepts, and Gorgonia ventalina. Elisellid gorgonians
are represented on the Atlantic reefs by Elisella barbadensis and Nicella
schmidtii. Among seleraxonian gorgonaceans the most common are Iciligorgia
schrammi, Erythropodium polyanthes, and E. cariboraeum.
The composition of octocoral communities changes along the crosssections in different reef zones. On the reef flat and on the outer reef slope
down to a depth of 10-20 m the symbiotic gorgonians dominate, being
represented there mostly by the genera Gorgonia, Eunicea, Pterogogia,
Pseudopterogorgia, Plexaurella, Plexaura and Briareum. The gorgonian
Pseudopterogorgia americana densely populates even the soft bottom
biotopes, attached to pieces of rubble and shells buried in the sediments
(Lasker and Coffroth 1983). On the slope downward domination gradually
shifts to the asymbiotic species of gorgonians, like Elisella, Nicella, Swiftia,
279
differed from the above-considered on the Pacific reefs by the relative
abundance of gorgonians. Most common among them were Rabdoplexaura,
Plexauroides, Echinogorgia, Acabaria, Mopsella, and Bebryce. The hard
octocorals Heliopora were numerous on flat shallows. This coral is common
on many reefs of the Indo-Pacific. Often it forms the micro atolls on submerged reef flats (Zann and Bolton 1985).
The above data show that in communities of octocorals on reefs of the
Indo-Pacific the aIcyonaceans most often largely dominate over the gorgonaceans. Only on reefs off the Vietnamese coasts were gorgonaceans
dominating, because of their ability better to withstand siltation, drops in
temperature and salinity during the winter monsoons peculiar to this area.
In contrast, on the reefs of the western Atlantic gorgonaceans absolutely
predominate over aIcyonaceans. Moreover, they are often a leading component of the sessile bottom fauna (Bayer 1961; Goldberg 1973; Opresko 1973;
Kinzie 1973; Preston and Preston 1975; Muzik 1982; Lasker and Coffroth
1983; Yoshioka and Yoshioka 1989). The number of colonies of gorgonians
reaches on many reefs 20-40m- 2 and the biomass over 0.5 kgm- 2 . Shannon's
index of species diversity (H') in octo coral communities often approaches
that of scleractinians: 1.5-33. Its maximum values they attain in upper
zones of the outward reef slope. The total number of species of octocorals in
coral communities of the western Atlantic varies between 16 on the Puerto
Rican reefs and 47 on reefs of Florida, which is close to that of scleractinians.
Most common reef gorgonians on reefs of this region belong to the two
families, Plexauridae and Gorgoniidae. Among them there are also several
species from the family. Paramuricidae (genus Swiftia) Elisellidae, and
the scleraxonian gorgonians Briareum, Erythropodium and Icilligorgia.
Among the plexaurid gorgonians the most common are Plexaura flexuosa,
P. homomalla, Plexaurella dichotoma, P. grisea, P. fusifera, Eunicea calyculata, E. asperula, E. tourneporti, E. pinta, E. succinea, Pseudoplexaura
circus, P. porosa, P. flagellosa, Muricea muricata, M. atlantica, Muriceopsis
potula, and M. flavida. The most common eugorgonians are Pseudopterogorgia americana, P. bipinnata, P. rigida, P. callos, P. elisabethae, P. acerosa,
Pterogorgia citrina, P. ancepts, and Gorgonia ventalina. Elisellid gorgonians
are represented on the Atlantic reefs by Elisella barbadensis and Nicella
schmidtii. Among seleraxonian gorgonaceans the most common are Iciligorgia
schrammi, Erythropodium polyanthes, and E. cariboraeum.
The composition of octocoral communities changes along the crosssections in different reef zones. On the reef flat and on the outer reef slope
down to a depth of 10-20 m the symbiotic gorgonians dominate, being
represented there mostly by the genera Gorgonia, Eunicea, Pterogogia,
Pseudopterogorgia, Plexaurella, Plexaura and Briareum. The gorgonian
Pseudopterogorgia americana densely populates even the soft bottom
biotopes, attached to pieces of rubble and shells buried in the sediments
(Lasker and Coffroth 1983). On the slope downward domination gradually
shifts to the asymbiotic species of gorgonians, like Elisella, Nicella, Swiftia,