294
Communities of Corals in Reef Ecosystems
the substrate in new places and start new coral colonies. This way of
vegetative multiplication happens often in massive, foliose and columnar
corals, like Porites, Agaricia, Montipora, and Meandrina (Bak 1976; Hughes
and Jackson 1980). In the ramose corals (Acropora sp.) it was observed in
zones of fast sedimentation (Connell 1973).
The fragments of living coral colonies fallen onto the bottom secrete a lot
of mucus, which covers it like a cocoon, and preserve polyps from
mechanical damage when the fragments are driven up from the bottom by
currents and waves (Bothwell 1981). Most fragments take root on the spot.
After several unsuccessful attempts to root the bulk of fragments produced
in the upper surf zones of the reef is driven down the reef slope. They
accumulate and then root in middle and lower depth zones, helping thereby
the formation of dense and varied coral communities there (Highsmith
1982). In common species of spawning ramose corals which actively use also
the vegetative way of multiplication, the share of the latter in their total
recruitment is high - 70-80% (Bak and Engel 1979; Tunnicliffe 1981). In
some Atlantic gorgonians this percentage was over 90% (Lasker and
Coffroth 1985), After long-lasting storms, when a mass of fragments ready
to be recruited appears on the reef, in some of its zones the forming of
monoclonal coral populations was observed (Bull 1982; Heyward and
Collins 1985).
The vegetative multiplication of corals by the bailing out of polyps was
discovered in one of the common opportunistic corals, Seriatopora histrix in
aquaria under stress conditions, such as exposure, excess or insufficient
illumination (Sammarco 1982). The coenosarc around polyps of a stressed
colony pull into the corallites and the polyps start to fall out of them.
Carried by currents and waves, they float to new places, where they settle
like the planulae and give start to the growth of new colonies. If the "pregnant" polyps of this viviparous coral bailout, they then hatch the planulae
that are in this naked and solitary state, enhancing so the distribution of
this species.
The propagation by buds is known in the scleractinian corals Asteros
milia (fam. Caryophyllidae), Balanophyllia, and Endocyathus (fam. Dendrophyllidae). Buds, looking like under-developed polyps, are joined
with the mother colony by a fragile connection. When this breaks, the buds
fall out and later settle and grow up into a new colony (Zibrowius 1985).
Somewhat similarly, the buds are produced by the solitary coral Fungia. It
separates periodically a part of its polyp together with an appropriate part of
corallite. The separated part of the colony soon grows up to a normal coral
(Wells 1966). The coral Goniopora stokesi also forms a kind of "buds",
which are small (2-4 cm) round colonies, appearing on the surface of the
mother colony. They then separate from it and give rise to new colonies
(Sheppard 1981b). The same way of propagation is used by the alcyonaceans
Xeniids. For example, Xenia macrospicularia periodically separates parts of
its colonies, which then settle nearby, forming gradually large settlements
Communities of Corals in Reef Ecosystems
the substrate in new places and start new coral colonies. This way of
vegetative multiplication happens often in massive, foliose and columnar
corals, like Porites, Agaricia, Montipora, and Meandrina (Bak 1976; Hughes
and Jackson 1980). In the ramose corals (Acropora sp.) it was observed in
zones of fast sedimentation (Connell 1973).
The fragments of living coral colonies fallen onto the bottom secrete a lot
of mucus, which covers it like a cocoon, and preserve polyps from
mechanical damage when the fragments are driven up from the bottom by
currents and waves (Bothwell 1981). Most fragments take root on the spot.
After several unsuccessful attempts to root the bulk of fragments produced
in the upper surf zones of the reef is driven down the reef slope. They
accumulate and then root in middle and lower depth zones, helping thereby
the formation of dense and varied coral communities there (Highsmith
1982). In common species of spawning ramose corals which actively use also
the vegetative way of multiplication, the share of the latter in their total
recruitment is high - 70-80% (Bak and Engel 1979; Tunnicliffe 1981). In
some Atlantic gorgonians this percentage was over 90% (Lasker and
Coffroth 1985), After long-lasting storms, when a mass of fragments ready
to be recruited appears on the reef, in some of its zones the forming of
monoclonal coral populations was observed (Bull 1982; Heyward and
Collins 1985).
The vegetative multiplication of corals by the bailing out of polyps was
discovered in one of the common opportunistic corals, Seriatopora histrix in
aquaria under stress conditions, such as exposure, excess or insufficient
illumination (Sammarco 1982). The coenosarc around polyps of a stressed
colony pull into the corallites and the polyps start to fall out of them.
Carried by currents and waves, they float to new places, where they settle
like the planulae and give start to the growth of new colonies. If the "pregnant" polyps of this viviparous coral bailout, they then hatch the planulae
that are in this naked and solitary state, enhancing so the distribution of
this species.
The propagation by buds is known in the scleractinian corals Asteros
milia (fam. Caryophyllidae), Balanophyllia, and Endocyathus (fam. Dendrophyllidae). Buds, looking like under-developed polyps, are joined
with the mother colony by a fragile connection. When this breaks, the buds
fall out and later settle and grow up into a new colony (Zibrowius 1985).
Somewhat similarly, the buds are produced by the solitary coral Fungia. It
separates periodically a part of its polyp together with an appropriate part of
corallite. The separated part of the colony soon grows up to a normal coral
(Wells 1966). The coral Goniopora stokesi also forms a kind of "buds",
which are small (2-4 cm) round colonies, appearing on the surface of the
mother colony. They then separate from it and give rise to new colonies
(Sheppard 1981b). The same way of propagation is used by the alcyonaceans
Xeniids. For example, Xenia macrospicularia periodically separates parts of
its colonies, which then settle nearby, forming gradually large settlements