126
Plankton in Coral-Reef Waters
high rates of heterotrophic respiration of the zooplankton alone in water
columns up the reef at night, which at the above biomass !ewe I should be
0.2-1g02 m- 2 day-l. Counting the respiration of bacterioplankton, it
should be 1.5-2.5g0 2 m- 2 day-l. Thus the traditional approach to measure
reef heterotrophic metabolism, counting only the respiration of benthos and
neglecting possible respiration of plankton, should be carefully reconsidered,
because with uncounted phytoplankton photosynthetic production of oxygen
(0.3-0.6g02 m- 2 day-l), and uncounted respiration of plankton (1.52.5 g O2 m -2) alone the range of the daily fluctuations of oxygen content in
waters over the reef could attain 1.5-2 g O2 m- 2 . But the diurnal fluctuations
of oxygen are still accepted as being induced by metabolic processes, which
go on in bottom communities.
The same concerns the roles of zooplankton in secondary production.
Its calculated approximate production, taking an average biomass of 0.51.5 g m -3, a specific production (P/B) of 0.15 per day, and water depth over
the reef of 3 m, should be 0.3-0.7 g m -3. Thus it could not be very far from
the production of zoo benthos even if its biomass is around 50-100gm- 2 .
So the roles of zooplankton and of zoo benthos in the reproduction of reef
trophic resources seem to be quite comparable. The reason for this conclusion could be deduced a priori from the fact of the high density and
variability of planktonovorous fish and fish larvae of most pelagic and
bottom reef fishes.
Plankton in Coral-Reef Waters
high rates of heterotrophic respiration of the zooplankton alone in water
columns up the reef at night, which at the above biomass !ewe I should be
0.2-1g02 m- 2 day-l. Counting the respiration of bacterioplankton, it
should be 1.5-2.5g0 2 m- 2 day-l. Thus the traditional approach to measure
reef heterotrophic metabolism, counting only the respiration of benthos and
neglecting possible respiration of plankton, should be carefully reconsidered,
because with uncounted phytoplankton photosynthetic production of oxygen
(0.3-0.6g02 m- 2 day-l), and uncounted respiration of plankton (1.52.5 g O2 m -2) alone the range of the daily fluctuations of oxygen content in
waters over the reef could attain 1.5-2 g O2 m- 2 . But the diurnal fluctuations
of oxygen are still accepted as being induced by metabolic processes, which
go on in bottom communities.
The same concerns the roles of zooplankton in secondary production.
Its calculated approximate production, taking an average biomass of 0.51.5 g m -3, a specific production (P/B) of 0.15 per day, and water depth over
the reef of 3 m, should be 0.3-0.7 g m -3. Thus it could not be very far from
the production of zoo benthos even if its biomass is around 50-100gm- 2 .
So the roles of zooplankton and of zoo benthos in the reproduction of reef
trophic resources seem to be quite comparable. The reason for this conclusion could be deduced a priori from the fact of the high density and
variability of planktonovorous fish and fish larvae of most pelagic and
bottom reef fishes.