252
Communities of Corals in Reef Ecosystems
approaches 800 species which belong to ca. 110 genera. They live in warm
waters in areas where the water temperature does not drop below 18-19 °C
in winter, and down to a depth of 80-100m, limited by light which they
need as symbiotic animals. The composition of the fauna of sclerectinians
and also the degree of its diversity vary in different reef areas and regions.
The total number of their genera attains its maximum in the region of
Indonesia-Philippines - North Australia, where it is over 70, with a total
number of species of 250-350 (Porter 1972; Veron 1985, 1986). The less
diverse fauna of scleractinians inhabits the reefs of the Atlantic basin,
including only 20 genera. This unevenness in their distribution is the
consequence of the relatively recent origin of this group of corals. The
processes of formation of scleractinian fauna are still in progress on the reefs
of the World Ocean (Veron 1985). One of the proofs for this assertion is the
separation of their faunas into the Indo-Pacific and the Atlantic basins. In
the young Atlantic Ocean the fauna of scleractinians is three to four times
poorer compared with that of the Indo-Pacific. Only the following six genera
out of 60-70 in the latter could be found on the Atlantic reefs: Acropora,
Cladocora, Favia, Madracis, Porites, Siderastrea. Moreover, among the
species of the above-listed common genera only one is common to both
regions - Siderastrea radians.
Among the great variety of modern taxa of hermatypic scleractinians
three groups could be distinguished. The first two have contrasting life
strategies: they are the r- and the k-strategists, and the third group is
intermediate between these two (Connell 1973). The first group of
opportunistic corals (r-strategists) live in small- or medium-sized colonies,
have a determined growth, reach early sexual maturity, and spend a larger
part of their energy in breeding. Most of them have a monthly cycle of
sexual multiplication. They have a life of short duration and a high growth
rate. The success of their survival is achieved by their intensive breeding,
which by their recruitment increases their chances in competition for the
hard substrate. They widely use for this purpose also the vegetative
multiplication by pieces of branches (cf. Sect. 7.4). The opportunistic corals
may survive different kinds of stress, like exposure, low salinity overheating,
pollution, and hot and turbid alkaline waters of reef shallows. Among these
opportunistic corals the most common on the Indo-Pacific reefs are
Stylophora pistillata, Psammocora contigua, Pocillopora damicornis,
Seriatopora histrix, and many species of the genera Montipora, Acropora,
and Pavona.
The group of conservative corals (k-strategists) use their energy mostly
for their own growth and metabolism. Their growth is practically unlimited.
Their old colonies can have diameters of 1-3 m. Correspondingly, they use
less energy for propagation and cope with the hard substrate available
through the formation of large colonies and thanks to their longevity. They
may live for tens and hundreds of years. Their cycles of breeding have an
Communities of Corals in Reef Ecosystems
approaches 800 species which belong to ca. 110 genera. They live in warm
waters in areas where the water temperature does not drop below 18-19 °C
in winter, and down to a depth of 80-100m, limited by light which they
need as symbiotic animals. The composition of the fauna of sclerectinians
and also the degree of its diversity vary in different reef areas and regions.
The total number of their genera attains its maximum in the region of
Indonesia-Philippines - North Australia, where it is over 70, with a total
number of species of 250-350 (Porter 1972; Veron 1985, 1986). The less
diverse fauna of scleractinians inhabits the reefs of the Atlantic basin,
including only 20 genera. This unevenness in their distribution is the
consequence of the relatively recent origin of this group of corals. The
processes of formation of scleractinian fauna are still in progress on the reefs
of the World Ocean (Veron 1985). One of the proofs for this assertion is the
separation of their faunas into the Indo-Pacific and the Atlantic basins. In
the young Atlantic Ocean the fauna of scleractinians is three to four times
poorer compared with that of the Indo-Pacific. Only the following six genera
out of 60-70 in the latter could be found on the Atlantic reefs: Acropora,
Cladocora, Favia, Madracis, Porites, Siderastrea. Moreover, among the
species of the above-listed common genera only one is common to both
regions - Siderastrea radians.
Among the great variety of modern taxa of hermatypic scleractinians
three groups could be distinguished. The first two have contrasting life
strategies: they are the r- and the k-strategists, and the third group is
intermediate between these two (Connell 1973). The first group of
opportunistic corals (r-strategists) live in small- or medium-sized colonies,
have a determined growth, reach early sexual maturity, and spend a larger
part of their energy in breeding. Most of them have a monthly cycle of
sexual multiplication. They have a life of short duration and a high growth
rate. The success of their survival is achieved by their intensive breeding,
which by their recruitment increases their chances in competition for the
hard substrate. They widely use for this purpose also the vegetative
multiplication by pieces of branches (cf. Sect. 7.4). The opportunistic corals
may survive different kinds of stress, like exposure, low salinity overheating,
pollution, and hot and turbid alkaline waters of reef shallows. Among these
opportunistic corals the most common on the Indo-Pacific reefs are
Stylophora pistillata, Psammocora contigua, Pocillopora damicornis,
Seriatopora histrix, and many species of the genera Montipora, Acropora,
and Pavona.
The group of conservative corals (k-strategists) use their energy mostly
for their own growth and metabolism. Their growth is practically unlimited.
Their old colonies can have diameters of 1-3 m. Correspondingly, they use
less energy for propagation and cope with the hard substrate available
through the formation of large colonies and thanks to their longevity. They
may live for tens and hundreds of years. Their cycles of breeding have an