Study of the Dynamics of Phosphorus
269
Table 5.2. Elements of balance of inorganic phosphorus exchange between some components of bottom biotopes of coral reefs and water column expressed as Ilg Pkg- l h- l
Kp
Object
Elements of balance
Ac
Ae
Ai
0.16
Living coral Stylophora
12.6
11.4
-1.2
0.35
Living coral Stylophora
31.7
28.8
-2.9
0.16
Dead coral covered with periphyton
31.0
18.0
-13.0
0.16
Coral rubble
11.5
21.5
+10.0
0.35
Coral rubble
56.0
53.9
-2.1
0.35
Coral sand
15.2
23.2
+8.0
Ac, consumption from water column; A" release; At, net change of P04-P concentration in water; K p , ambient P04-P content in water, Ilmoll-1.
As mentioned above, the experimental study of phosphate exchange flows
between the benthic biotopes and the water column might be accomplished
either in an enclosure, which is fixed above the bottom area and safely isolates
the enclosed volume from the surrounding water, or in an aquarium. With the
latter, the corresponding measurement can be performed with some basic elements of hard-bottom biotopes, like pieces of rocks covered with periphyton,
coral rubble, pebbles, hydrophytes, sponges, or corals.
The working solution for these experiments is best prepared from
32pOl- batches. It is cheaper to use in significant quantities for large volume
enclosures, and also less quenched than 33p-phosphate. If the aquarium
version is used, the latter is filled with 3-101 of natural water prefiltered
through 0.45-f..lm pore size GF filters. Then the ambient content of reactive
phosphate is measured in it by the standard method. If this content appears
to be less than 0.4 f..lmoll-l, it should be adjusted to this level by the addition of a P04-P carrier solution to the aquarium. Then the working solution
of 32P04 is added in a quantity sufficient to create the initial actual radioactivity in the aquarium close to 0.5-110 6 cpm l-l. Its content is carefully mixed
and a 1-2-1 volume of water is transferred from it into another control aquarium. Then the benthic object of some 100-200 g weight per 21 of water is placed
into the experimental aquarium. Both aquaria are incubated for 3-5h, the
water in them being periodically or continuously slowly mixed during the incubation. At the end of the incubation, the subsamples from both the control
and experimental aquaria are tested for the radioactivity of 32P04 (Ro and
R i , cpml- 1 ) and for the absolute content of inorganic phosphate (Po and
Pi, f..lgPl-1).
The first values, Ro and R i , are measured as follows: 0.1 ml of carrier
solution containing 1 mmoll- 1 of P04 + 1 ml of mixture containing 2 g of
NaOH + 2g of CaC03 + 3g of ferrous ammonium sulfate in 100ml of
water are added to three parallel 25-ml aliquots taken from the above sub-
269
Table 5.2. Elements of balance of inorganic phosphorus exchange between some components of bottom biotopes of coral reefs and water column expressed as Ilg Pkg- l h- l
Kp
Object
Elements of balance
Ac
Ae
Ai
0.16
Living coral Stylophora
12.6
11.4
-1.2
0.35
Living coral Stylophora
31.7
28.8
-2.9
0.16
Dead coral covered with periphyton
31.0
18.0
-13.0
0.16
Coral rubble
11.5
21.5
+10.0
0.35
Coral rubble
56.0
53.9
-2.1
0.35
Coral sand
15.2
23.2
+8.0
Ac, consumption from water column; A" release; At, net change of P04-P concentration in water; K p , ambient P04-P content in water, Ilmoll-1.
As mentioned above, the experimental study of phosphate exchange flows
between the benthic biotopes and the water column might be accomplished
either in an enclosure, which is fixed above the bottom area and safely isolates
the enclosed volume from the surrounding water, or in an aquarium. With the
latter, the corresponding measurement can be performed with some basic elements of hard-bottom biotopes, like pieces of rocks covered with periphyton,
coral rubble, pebbles, hydrophytes, sponges, or corals.
The working solution for these experiments is best prepared from
32pOl- batches. It is cheaper to use in significant quantities for large volume
enclosures, and also less quenched than 33p-phosphate. If the aquarium
version is used, the latter is filled with 3-101 of natural water prefiltered
through 0.45-f..lm pore size GF filters. Then the ambient content of reactive
phosphate is measured in it by the standard method. If this content appears
to be less than 0.4 f..lmoll-l, it should be adjusted to this level by the addition of a P04-P carrier solution to the aquarium. Then the working solution
of 32P04 is added in a quantity sufficient to create the initial actual radioactivity in the aquarium close to 0.5-110 6 cpm l-l. Its content is carefully mixed
and a 1-2-1 volume of water is transferred from it into another control aquarium. Then the benthic object of some 100-200 g weight per 21 of water is placed
into the experimental aquarium. Both aquaria are incubated for 3-5h, the
water in them being periodically or continuously slowly mixed during the incubation. At the end of the incubation, the subsamples from both the control
and experimental aquaria are tested for the radioactivity of 32P04 (Ro and
R i , cpml- 1 ) and for the absolute content of inorganic phosphate (Po and
Pi, f..lgPl-1).
The first values, Ro and R i , are measured as follows: 0.1 ml of carrier
solution containing 1 mmoll- 1 of P04 + 1 ml of mixture containing 2 g of
NaOH + 2g of CaC03 + 3g of ferrous ammonium sulfate in 100ml of
water are added to three parallel 25-ml aliquots taken from the above sub-