300
Morphology and Ecological Physiology of Corals
The percentage of dry weight in colonies of scleractinian corals varies
usually within 70 to 85% with their specific weight being 2.5-3gcm- 3 . In
octocorals it varies within wide limits: 10 to 60%, depending upon the
content of spicular calcareous meterial in them (Lewis and Post 1982). The
substance of organic matrix (mainly polyps and coenosarc) comprise in
colonies of scleractinian corals 5-20% of dry weight, or 1O-70mgCg- 1 of
dry weight of a colony (Table 8.1). The largest content of total organic
matter was recorded in colonies of corals Montipora and Porites, living in
shallow biotopes and subjected to excess illumination. The biomass of
polyps in them comprises only 10-17% of the total organic matter, while in
most of other corals its share is much more (Table 8.1). In octocorals the
content of organic matter is between 10 to 25% and only in xeniids, which
actually do not have skeletal elements, it could be over 70%. In
gorgonaceans 50-80% of the material in colony is composed of the
calcareous skeleton, and 6-30% of axial cord material (Lewis and Post
1982). The dry decalcinated mass of living tissue in scleractinian corals
contains 10-20% ash, 20-25% protein and 10-30% lipids (Edmunds and
Davies 1986).The individual wet biomass of polyps in them varies from
0.3-1 mg in colonies of the corals Seriatopora and Stylophora to several
grams in Symphillia or Fungia. The content of organic carbon per one polyp
in corals with small polyps (acroporids, poritids) varied within 15 to 140llg,
in corals with medium polyps (Leptastrea, Pavona, Meruline, Galaxea)
within 0.6-3 mg, and in corals with large polyps (faviids, Symphillia,
Fungia) between tens and hundreds of milligrams (Table 8.1). The biomass
of the polyps of scleractinians comprises usually 20-40% of the total organic
matter or 0.5-1 % of dry weight of a colony. Most octocorals have small to
medium sized polyps 0.5-3mg of wet weight or 40-250llgCSp.-l (Table
8.2).
The number of zooxanthellae in corals is rather stable: 1-5 x 10 6 cells
per 1 cm 2 surface of their colonies (Table 8.3). Calculated per 1 polyp, small
or medium size, it varied either in scleractinians or octocorals within 20-60
x 10 3 cells. In scleractinians the biomass of zooxanthellae was found to be
30-1001lg Cg- 1 of dry weight of a colony, and in octocorals 0.51.5mgCg- 1 (Tables 8.1, 8.2). For the evaluation of animal and plant
components of comparative importance in polyp tissues it was important to
estimate the ratio of biomass of zooxanthellae to biomass of polyps. First, its
estimation had given very high values for this ratio - 20-40% in protein
(Muscatine and Cernichari 1969). But these data seemed to be exaggerated,
maybe because of the incomplete purification of zooxanthellae from the
animal tissues of polyps. Later, it was shown that as to protein this ratio in
polyps of the coral Pocillopora is close to 5% (Muscatine and Porter 1977).
The same ratio of their biomasses, expressed in units of organic carbon,
varied most often between 1-3%, estimated in 23 species of scleractinians
and in 10 species of octocorals (Sorokin 1981a, 1984b; cf. Tables 8.1, 8.2).
Other estimates gave values of this ratio with 1-5% in the corals Acropora,
Morphology and Ecological Physiology of Corals
The percentage of dry weight in colonies of scleractinian corals varies
usually within 70 to 85% with their specific weight being 2.5-3gcm- 3 . In
octocorals it varies within wide limits: 10 to 60%, depending upon the
content of spicular calcareous meterial in them (Lewis and Post 1982). The
substance of organic matrix (mainly polyps and coenosarc) comprise in
colonies of scleractinian corals 5-20% of dry weight, or 1O-70mgCg- 1 of
dry weight of a colony (Table 8.1). The largest content of total organic
matter was recorded in colonies of corals Montipora and Porites, living in
shallow biotopes and subjected to excess illumination. The biomass of
polyps in them comprises only 10-17% of the total organic matter, while in
most of other corals its share is much more (Table 8.1). In octocorals the
content of organic matter is between 10 to 25% and only in xeniids, which
actually do not have skeletal elements, it could be over 70%. In
gorgonaceans 50-80% of the material in colony is composed of the
calcareous skeleton, and 6-30% of axial cord material (Lewis and Post
1982). The dry decalcinated mass of living tissue in scleractinian corals
contains 10-20% ash, 20-25% protein and 10-30% lipids (Edmunds and
Davies 1986).The individual wet biomass of polyps in them varies from
0.3-1 mg in colonies of the corals Seriatopora and Stylophora to several
grams in Symphillia or Fungia. The content of organic carbon per one polyp
in corals with small polyps (acroporids, poritids) varied within 15 to 140llg,
in corals with medium polyps (Leptastrea, Pavona, Meruline, Galaxea)
within 0.6-3 mg, and in corals with large polyps (faviids, Symphillia,
Fungia) between tens and hundreds of milligrams (Table 8.1). The biomass
of the polyps of scleractinians comprises usually 20-40% of the total organic
matter or 0.5-1 % of dry weight of a colony. Most octocorals have small to
medium sized polyps 0.5-3mg of wet weight or 40-250llgCSp.-l (Table
8.2).
The number of zooxanthellae in corals is rather stable: 1-5 x 10 6 cells
per 1 cm 2 surface of their colonies (Table 8.3). Calculated per 1 polyp, small
or medium size, it varied either in scleractinians or octocorals within 20-60
x 10 3 cells. In scleractinians the biomass of zooxanthellae was found to be
30-1001lg Cg- 1 of dry weight of a colony, and in octocorals 0.51.5mgCg- 1 (Tables 8.1, 8.2). For the evaluation of animal and plant
components of comparative importance in polyp tissues it was important to
estimate the ratio of biomass of zooxanthellae to biomass of polyps. First, its
estimation had given very high values for this ratio - 20-40% in protein
(Muscatine and Cernichari 1969). But these data seemed to be exaggerated,
maybe because of the incomplete purification of zooxanthellae from the
animal tissues of polyps. Later, it was shown that as to protein this ratio in
polyps of the coral Pocillopora is close to 5% (Muscatine and Porter 1977).
The same ratio of their biomasses, expressed in units of organic carbon,
varied most often between 1-3%, estimated in 23 species of scleractinians
and in 10 species of octocorals (Sorokin 1981a, 1984b; cf. Tables 8.1, 8.2).
Other estimates gave values of this ratio with 1-5% in the corals Acropora,