178
Reef Zoobenthos
P n ~---------------------,
iU
- -U ~----~--------------~
-iO
o
7
z
J
Fig. 5.3. Light dependence curves of net photosynthesis (Pllllg 02 g-I h -I) in symbiotic
sponges Carterosponia (1) and Cascopongia (2); L light intensity, E m- 2 h- I . (After
Wilkinson and Trott 1985)
sponge photosynthesis ranges within a light intensity of 30-17011 E m -2 s or
50-150Wm- 2 (Fig. 5.3). This level of illumination is somewhat higher than
that for corals. The same as in corals, light adaptation to low illumination
was observed also in symbiotic sponges (Wilkinson 1981; Wilkinson and
Trott 1985). The parameters of Pt and Mt in some mass species of reef
sponges are given in Table 5.1. The chlorophyll content in sponges varied in
different species from 10 to 40llgg-1 of wet body weight. The pigment
system of algal symbionts in sponges has the absorption maximum of 664 nm
(Wilkinson 1983b, 1985).
The phototrophic sponges usually dominate in most reef-flat and outer
reef-slope biotopes (Wilkinson 1985, 1989). For example, in some biotopes
of the Davis reef (GBR of Australia) these sponges comprised over 80% of
the total species number of sponges. In seven out of nine common species of
sponges the ratios Pt/Mt at midday were around 3 (Wilkinson 1983b).
5.2.2 Community Structure and Features of Ecology
The reef benthic communities are inhabited by more than 500 species of
sponges from three of their basic classes. Demospongia, Calcarea and
Sclerospongia. About 90-95% of them belong to demospo[J.ges, 4-8% to
Calcarea and 1-2% to sclerosponges. The demosponges have their skeleton
armatures consisting of collagen and spongin fiber mass armed with the fine
silicate needle-shaped spicules. The calcareous sponges are armed with
3-4-ray, star-like calcite spicules. The sclerosponges form a massive
aragonite base, but their body mass is armed with silicate spicules. Some
20% of the total sponge community consists of species of the boring sponges
(Pang 1973; Riitzler 1975). The sponges fauna of the Caribbean reefs (down
Reef Zoobenthos
P n ~---------------------,
iU
- -U ~----~--------------~
-iO
o
7
z
J
Fig. 5.3. Light dependence curves of net photosynthesis (Pllllg 02 g-I h -I) in symbiotic
sponges Carterosponia (1) and Cascopongia (2); L light intensity, E m- 2 h- I . (After
Wilkinson and Trott 1985)
sponge photosynthesis ranges within a light intensity of 30-17011 E m -2 s or
50-150Wm- 2 (Fig. 5.3). This level of illumination is somewhat higher than
that for corals. The same as in corals, light adaptation to low illumination
was observed also in symbiotic sponges (Wilkinson 1981; Wilkinson and
Trott 1985). The parameters of Pt and Mt in some mass species of reef
sponges are given in Table 5.1. The chlorophyll content in sponges varied in
different species from 10 to 40llgg-1 of wet body weight. The pigment
system of algal symbionts in sponges has the absorption maximum of 664 nm
(Wilkinson 1983b, 1985).
The phototrophic sponges usually dominate in most reef-flat and outer
reef-slope biotopes (Wilkinson 1985, 1989). For example, in some biotopes
of the Davis reef (GBR of Australia) these sponges comprised over 80% of
the total species number of sponges. In seven out of nine common species of
sponges the ratios Pt/Mt at midday were around 3 (Wilkinson 1983b).
5.2.2 Community Structure and Features of Ecology
The reef benthic communities are inhabited by more than 500 species of
sponges from three of their basic classes. Demospongia, Calcarea and
Sclerospongia. About 90-95% of them belong to demospo[J.ges, 4-8% to
Calcarea and 1-2% to sclerosponges. The demosponges have their skeleton
armatures consisting of collagen and spongin fiber mass armed with the fine
silicate needle-shaped spicules. The calcareous sponges are armed with
3-4-ray, star-like calcite spicules. The sclerosponges form a massive
aragonite base, but their body mass is armed with silicate spicules. Some
20% of the total sponge community consists of species of the boring sponges
(Pang 1973; Riitzler 1975). The sponges fauna of the Caribbean reefs (down