384
Biogeochemical Metabolism and Energy Flows in Reef Ecosystems
(excluding the respiration of the plants themselves). The global annual gross
primary production in reef systems should be then about 7-9 x 10 8 t C,
which contributes 1.5-2% to the total primary organic production in the
World Ocean. The net production of organic carton was evaluated as 20 x
10 6 tC, of which 3 x 10 6 t is buried in sediments, 15 x 10 6 t is exported to the
surrounding ocean and 2 x 10 6 t can be used by man (Crossland et al. 1991).
When evaluating this contribution of coral reef ecosystems to the global
oceanic productivity we have to keep in mind that it is several times more
than the joint primary production in the productive zones of upwelling, from
where a large portion of the total world fish catch comes (Muscatine 1980).
With respect to the above integral primary production, the global annual
flow of elements in reef ecosystems could be expressed by the following
levels: N = 2.7 x 10 7 t, P = 1.3 x 10 6 t, Fe = 3 x 10 6 t, Mn = 3 x 10 5 t.
The coral reefs of the World Ocean are the main generators of calcareous
sediments on the Earth. The size of the global processes of lime
sedimentation in coral reefs could be assumed to be close to 2 x
10 9 t CaC03 year-I Besides ongmating such a large-scale global
biogeochemical process of calcium sedimentation from seawater, coral reef
systems regulate, together with calcium, also carbon dioxide, so that they
are one of the most important regulators of CO2 content in the World
Ocean. In conjunction with the now developing global "greenhouse" effect,
caused by the anthropogenically induced increase in CO2 content in the
atmosphere, the CO2 uptake by coral reefs is becoming more and more
important. The progressive destabilization and destruction of reef systems
may enhance the dangers from the "green house" effect which, in itself,
endangers also the coral reefs' very existence, killing them by overheating,
and by drowing them during the expected elevation of the sea-level. Thus,
the two processes - destabilization of the reef systems and buildup of the
"green house" effect - are cumulative, reinforcing each other, which could
have a drastic impact on environmental conditions on which the survival of
mankind, depends, unless both are stopped (Hopley and Kinsey 1988). By
the middle of the twenty-fin,t century a rise of 0.2-1.4 m in sea level is
expected.
10.3 Model Studies and Energy Budget in Reef Ecosystems
One of the ways for understanding the mechanisms of functioning of coral
reef ecosystems is the generalizations at the level of the schemes of trophic
or energy relationships between its component communities, representing
different links in the food chain. Such generalizations seem to lead to the
next step - the composition of models of coral reef ecosystems as a tool for
their further holistic investigation, including the influence of anthropogenic
Biogeochemical Metabolism and Energy Flows in Reef Ecosystems
(excluding the respiration of the plants themselves). The global annual gross
primary production in reef systems should be then about 7-9 x 10 8 t C,
which contributes 1.5-2% to the total primary organic production in the
World Ocean. The net production of organic carton was evaluated as 20 x
10 6 tC, of which 3 x 10 6 t is buried in sediments, 15 x 10 6 t is exported to the
surrounding ocean and 2 x 10 6 t can be used by man (Crossland et al. 1991).
When evaluating this contribution of coral reef ecosystems to the global
oceanic productivity we have to keep in mind that it is several times more
than the joint primary production in the productive zones of upwelling, from
where a large portion of the total world fish catch comes (Muscatine 1980).
With respect to the above integral primary production, the global annual
flow of elements in reef ecosystems could be expressed by the following
levels: N = 2.7 x 10 7 t, P = 1.3 x 10 6 t, Fe = 3 x 10 6 t, Mn = 3 x 10 5 t.
The coral reefs of the World Ocean are the main generators of calcareous
sediments on the Earth. The size of the global processes of lime
sedimentation in coral reefs could be assumed to be close to 2 x
10 9 t CaC03 year-I Besides ongmating such a large-scale global
biogeochemical process of calcium sedimentation from seawater, coral reef
systems regulate, together with calcium, also carbon dioxide, so that they
are one of the most important regulators of CO2 content in the World
Ocean. In conjunction with the now developing global "greenhouse" effect,
caused by the anthropogenically induced increase in CO2 content in the
atmosphere, the CO2 uptake by coral reefs is becoming more and more
important. The progressive destabilization and destruction of reef systems
may enhance the dangers from the "green house" effect which, in itself,
endangers also the coral reefs' very existence, killing them by overheating,
and by drowing them during the expected elevation of the sea-level. Thus,
the two processes - destabilization of the reef systems and buildup of the
"green house" effect - are cumulative, reinforcing each other, which could
have a drastic impact on environmental conditions on which the survival of
mankind, depends, unless both are stopped (Hopley and Kinsey 1988). By
the middle of the twenty-fin,t century a rise of 0.2-1.4 m in sea level is
expected.
10.3 Model Studies and Energy Budget in Reef Ecosystems
One of the ways for understanding the mechanisms of functioning of coral
reef ecosystems is the generalizations at the level of the schemes of trophic
or energy relationships between its component communities, representing
different links in the food chain. Such generalizations seem to lead to the
next step - the composition of models of coral reef ecosystems as a tool for
their further holistic investigation, including the influence of anthropogenic