316
Morphology and Ecological Physiology of Corals
Table 8.5. Coefficients Kp in corals of the Heron I. reefs (cf. text)
Period of the
Kp
light day, hours.
8-9
11.8
9-10
10.8
10-11
9.1
2
2.f/l
.f/l/l
Periods of the
light day, hours.
11-12
12-13
13-14
l.f/l
1/1/10
:J
Kp
9.7
10.2
11.1
Periods of the
Kp
light day, hours.
14-15
11.8
15-16
12.8
16-17
14.0
Fig. 8.11. Light saturation curve of gross photosynthesis (Pr, relative values) in the coral
Acropora cervicornis; I light intensity, Em- 2 h- 1 . (Modified after Chalker and Taylor
1978)
(Fig. 8.11), the abscissa going parallel till the maximal light intensity
peculiar to the tropical zone, 250-350wtm- 2 , will be reached. Thus the
saturation light intensity in corals is close to 20-30% PARS. Within its
limits of 90-20% PARS (in some corals even down to 10% PARS) the rate
of photosynthesis is actually independent of light intensity (Titlyanov et al.
1988b). Below the light intensity of 20-10% PARS (e.g., at depths more
than 20- 30 m in transparent shelf waters), the their photosynthesis rate
starts to drop (Drew 1973; Fig. 8.14).
The curves of light saturation of photosynthesis appear to be different in
corals living in illuminated and in shadowed habitats, thus demonstrating the
light adaptation of the latter (Figs. 8.12, 8.13). These curves measured in
corals taken from deep reef zones or from caves or grottos and so adapted
to low illumination have steeper slopes in their initial parts. These corals
reach sooner the saturation point. Saturation light intensity in the corals is
40-50wtm- 2 compared with 90-110wtm- 2 in normal corals living in full
light (Chalker et al. 1983; Battey and Porter 1988; Titlyanov et al. 1988a,b;
Tchabardgy and Fam Van Huen 1988).
The compensation point, where the net photosynthesis approaches zero,
is reached by light-adapted corals at twofold less illumination. Therefore,
their potential photosynthesis rate measured in moderate light is higher than
in normal corals (Zvalinski et al. 1980; Titlyanov 1981; Falkowsky and
Dubinsky 1981). This increase is not accompanied by an increase in
Morphology and Ecological Physiology of Corals
Table 8.5. Coefficients Kp in corals of the Heron I. reefs (cf. text)
Period of the
Kp
light day, hours.
8-9
11.8
9-10
10.8
10-11
9.1
2
2.f/l
.f/l/l
Periods of the
light day, hours.
11-12
12-13
13-14
l.f/l
1/1/10
:J
Kp
9.7
10.2
11.1
Periods of the
Kp
light day, hours.
14-15
11.8
15-16
12.8
16-17
14.0
Fig. 8.11. Light saturation curve of gross photosynthesis (Pr, relative values) in the coral
Acropora cervicornis; I light intensity, Em- 2 h- 1 . (Modified after Chalker and Taylor
1978)
(Fig. 8.11), the abscissa going parallel till the maximal light intensity
peculiar to the tropical zone, 250-350wtm- 2 , will be reached. Thus the
saturation light intensity in corals is close to 20-30% PARS. Within its
limits of 90-20% PARS (in some corals even down to 10% PARS) the rate
of photosynthesis is actually independent of light intensity (Titlyanov et al.
1988b). Below the light intensity of 20-10% PARS (e.g., at depths more
than 20- 30 m in transparent shelf waters), the their photosynthesis rate
starts to drop (Drew 1973; Fig. 8.14).
The curves of light saturation of photosynthesis appear to be different in
corals living in illuminated and in shadowed habitats, thus demonstrating the
light adaptation of the latter (Figs. 8.12, 8.13). These curves measured in
corals taken from deep reef zones or from caves or grottos and so adapted
to low illumination have steeper slopes in their initial parts. These corals
reach sooner the saturation point. Saturation light intensity in the corals is
40-50wtm- 2 compared with 90-110wtm- 2 in normal corals living in full
light (Chalker et al. 1983; Battey and Porter 1988; Titlyanov et al. 1988a,b;
Tchabardgy and Fam Van Huen 1988).
The compensation point, where the net photosynthesis approaches zero,
is reached by light-adapted corals at twofold less illumination. Therefore,
their potential photosynthesis rate measured in moderate light is higher than
in normal corals (Zvalinski et al. 1980; Titlyanov 1981; Falkowsky and
Dubinsky 1981). This increase is not accompanied by an increase in