9 Nutrition of Corals
Above it was mentioned that most scleractinian corals and more than half of
the taxa of octocorals inhabiting coral reefs have algal symbionts in their
tissues - the zooxanthellae. The endosymbiosis enables them to use solar
energy. Simultaneously, coral polyps are able to feed as heterotrophs. The
autotrophic and heterotrophic nutrition of corals and the relative
importance of these sources in their energy balance have been recognized
long ago as key problems of biology and ecology not only of the corals
themselves but also of the coral reef ecosystems as a whole (Odum and
Odum 1955, 1956).
9.1 Autotrophic Feeding of Corals
The autotrophic nutrition of corals proceeds by the translocation of the
photosynthates, produced by their symbiotic algae, the zooxanthellae, into
the tissues of polyps. The value of photosynthetic production of corals is
usually expressed in units of gross photosynthesis (Pt ) or of net
photosynthesis (P n). The latter is calculted as the difference between Pt and
the total respiration of the coral, including its algal component (Mt ): P n = Pt
- M t • The net photosynthetic production of the zooxanthellae themselves
(P nz) is equal to: P nz = Pt - Mz , if Mz = respiration of zooxanthellae. The
importance of autotrophic production in the energy balance of corals could
be calculated as the ratio of net photosynthetic production of zooxanthellae,
translocated to the animal tissues (P nz . T), to the respiration of animal
tissues of the polyp (Ma). This ratio is named CZAR (contribution of
zooxanthellae to animal respiration). CZAR = (Pnz X T)/Ma, if Ma = Mt -
Mz , and T is the part of P nz, translocated to the polyp.
The rates of photosynthesis and respitation in corals were measured by
the oxygen and radiocarbon methods. The latter method yields values which
seem to be closer to the net photosynthesis (Cooksey and Cooksey 1972;
Scott and litts 1977). But according to Drew (1973) it could be rather equal
to the gross photosynthesis. Their measurements were accomplished in
closed vessels or containers, as well as in flow respirometers. As for the
Above it was mentioned that most scleractinian corals and more than half of
the taxa of octocorals inhabiting coral reefs have algal symbionts in their
tissues - the zooxanthellae. The endosymbiosis enables them to use solar
energy. Simultaneously, coral polyps are able to feed as heterotrophs. The
autotrophic and heterotrophic nutrition of corals and the relative
importance of these sources in their energy balance have been recognized
long ago as key problems of biology and ecology not only of the corals
themselves but also of the coral reef ecosystems as a whole (Odum and
Odum 1955, 1956).
9.1 Autotrophic Feeding of Corals
The autotrophic nutrition of corals proceeds by the translocation of the
photosynthates, produced by their symbiotic algae, the zooxanthellae, into
the tissues of polyps. The value of photosynthetic production of corals is
usually expressed in units of gross photosynthesis (Pt ) or of net
photosynthesis (P n). The latter is calculted as the difference between Pt and
the total respiration of the coral, including its algal component (Mt ): P n = Pt
- M t • The net photosynthetic production of the zooxanthellae themselves
(P nz) is equal to: P nz = Pt - Mz , if Mz = respiration of zooxanthellae. The
importance of autotrophic production in the energy balance of corals could
be calculated as the ratio of net photosynthetic production of zooxanthellae,
translocated to the animal tissues (P nz . T), to the respiration of animal
tissues of the polyp (Ma). This ratio is named CZAR (contribution of
zooxanthellae to animal respiration). CZAR = (Pnz X T)/Ma, if Ma = Mt -
Mz , and T is the part of P nz, translocated to the polyp.
The rates of photosynthesis and respitation in corals were measured by
the oxygen and radiocarbon methods. The latter method yields values which
seem to be closer to the net photosynthesis (Cooksey and Cooksey 1972;
Scott and litts 1977). But according to Drew (1973) it could be rather equal
to the gross photosynthesis. Their measurements were accomplished in
closed vessels or containers, as well as in flow respirometers. As for the