Biogeochemical Metabolism of Other Elements
383
per year) was estimated to come from the lagoon because of its relatively
large area, while the production per m 2 there was about three times less
than in biotopes of patch reefs of the reef flat. The net photosynthetic
production in biotopes of the outer reef slope, including the fore-reef zone,
was found to be close to zero.
The biogeochemical metabolism of carbon in reef communities includes
also the process of growth of the lime skeletons of benthic animals and of
calcareous algae, i.e., the process of calcification. Its rates in reef
communities is extremely high, ranging from 1 to 20 kg CaS03 m -2 year-I.
This corresponds to diurnal values of 3 to 50 g of CaC02 or 0.24 g C m -2 day-I, which is close to the lower level of carbon flow rates by
photosynthesis processes.
10.2 Biogeochemical Metabolism of Other Elements
Both the photosynthetic production and the destruction of organic matter,
as well as the calcification processes, are the energy and chemical
backgrounds of the biogeochemical turnover of elements coupled with them,
which are the components of the living tissues and the skeletal material of
reef organisms, and also of some other elements whose turnover in the
aquatic habitats is linked with the formetion of redox zones in the columns
of bottom sediments (Livingston and Thomson 1971; Howard and Brown
1984). Among these elements N, P, S, Fe, Mn, Ba, Cd and Co (Shen et al.
1987; Brown et al. 1991) . The dynamics of the first four elements have been
discussed above (cf. Sects. 2.2, 4.1). Here, we give only approximate
calculations for them, based upon the C: N: P ratios, which in the reef
ecosystem, because of the semiclosed cycles of nutrients in their plant, and
especially animal symbiotic associations, looks like 100: 3: 0.15 by weight
(Atkinson 1981a). Thus, with an average primary production in reef plant
communities of 4 g Cm- 2 day-I, the flow rates of Nand P in them should be
ca. 120 and 15mgm- 2 day-l, respectively. The ratios of C:Fe:Mn in the
aquatic plant biomass are close to 100: 0.3: 0.03 by weight. Thus, the flows
of Fe and Mn coupled with the primary production in reef communities
could be evaluated at approximately 12 mg and 1 mg m -2 day-I respectively.
The flow of cobaltum could be coupled only with the microbieal biosynthesis (Sorokin 1972). With its rate in reef environments of
0.5 g C m -2 day-I, the flow cobalt should be at the level of lOOllg m -2day-l.
The global evaluations of biogeochemical activity of the reef ecosystems
are based upon their total area of 6 x 10 5 km 2 in the World Ocean which
includes 15% of its shallows at 0-30m depth, or about 0.2% of its total area
(S.Y. Smith 1978; Grossland et al. 1991). The primary production on this
area has been evaluated, as shown above, with 1.5kgCm- 2 year- 1
383
per year) was estimated to come from the lagoon because of its relatively
large area, while the production per m 2 there was about three times less
than in biotopes of patch reefs of the reef flat. The net photosynthetic
production in biotopes of the outer reef slope, including the fore-reef zone,
was found to be close to zero.
The biogeochemical metabolism of carbon in reef communities includes
also the process of growth of the lime skeletons of benthic animals and of
calcareous algae, i.e., the process of calcification. Its rates in reef
communities is extremely high, ranging from 1 to 20 kg CaS03 m -2 year-I.
This corresponds to diurnal values of 3 to 50 g of CaC02 or 0.24 g C m -2 day-I, which is close to the lower level of carbon flow rates by
photosynthesis processes.
10.2 Biogeochemical Metabolism of Other Elements
Both the photosynthetic production and the destruction of organic matter,
as well as the calcification processes, are the energy and chemical
backgrounds of the biogeochemical turnover of elements coupled with them,
which are the components of the living tissues and the skeletal material of
reef organisms, and also of some other elements whose turnover in the
aquatic habitats is linked with the formetion of redox zones in the columns
of bottom sediments (Livingston and Thomson 1971; Howard and Brown
1984). Among these elements N, P, S, Fe, Mn, Ba, Cd and Co (Shen et al.
1987; Brown et al. 1991) . The dynamics of the first four elements have been
discussed above (cf. Sects. 2.2, 4.1). Here, we give only approximate
calculations for them, based upon the C: N: P ratios, which in the reef
ecosystem, because of the semiclosed cycles of nutrients in their plant, and
especially animal symbiotic associations, looks like 100: 3: 0.15 by weight
(Atkinson 1981a). Thus, with an average primary production in reef plant
communities of 4 g Cm- 2 day-I, the flow rates of Nand P in them should be
ca. 120 and 15mgm- 2 day-l, respectively. The ratios of C:Fe:Mn in the
aquatic plant biomass are close to 100: 0.3: 0.03 by weight. Thus, the flows
of Fe and Mn coupled with the primary production in reef communities
could be evaluated at approximately 12 mg and 1 mg m -2 day-I respectively.
The flow of cobaltum could be coupled only with the microbieal biosynthesis (Sorokin 1972). With its rate in reef environments of
0.5 g C m -2 day-I, the flow cobalt should be at the level of lOOllg m -2day-l.
The global evaluations of biogeochemical activity of the reef ecosystems
are based upon their total area of 6 x 10 5 km 2 in the World Ocean which
includes 15% of its shallows at 0-30m depth, or about 0.2% of its total area
(S.Y. Smith 1978; Grossland et al. 1991). The primary production on this
area has been evaluated, as shown above, with 1.5kgCm- 2 year- 1