204
Reef Zoo benthos
accumulators of carbonaceous material were accomplished by the fenestrine
bryozoans. Later in the Cenozoic, their function was taken over by the
scleractinian corals. Modern bryozoans also participate in the processes of
reef construction, being agents of consolidation of carbonaceous material.
They excrete a very sticky polysaccharide substance to glue their colonies to
the rock surfaces (Soule and Soule 1976). This glue then is quickly
impregnated by carbonate and forms a solid massive crust, which
consolidates the surfaces of rubble, and of dead corals, and thus cements the
trenches and holes in the flat and patch-reef rocks (Garrett et al. 1971;
Cuffey 1977). The branching bryozoan colonies keep and accumulate sand
and rubble in trenches and caverns participating also in the processes of
reef-rock consolidation. The material of bryozoan skeletons is a remarkable
source of carbonaceous material in bottom sediments (Cuffey 1973).
5.S Foraminifera and Other Benthic Protozoa
One of the most specific features of reef benthic communities is an extreme
abundance of foraminifera. These shelled benthic protozoans compose a
large part of the microbenthos in the soft bottom biotopes and produce over
50% of carbonaceous material of the coral sands (Renaud-Morn ant et al.
1971). The sedentary forams densely inhabit also the surfaces of rubble
material, the leaves of weeds and grasses (Glenn et al. 1981). Forams belong
to the phylum Sarcomastigophora. The cells of these protozoans live in
one-chamber or multichamber shells. The latter might contain up to 100
chambers. The shells are constructed from the chitin-like material incrusted
by calcium carbonate which the cell extracts from seawater. The size of the
shells of most forams varies usually within 0.5-1.5 mm, but some families
include one or several species of gigantic symbiotic forams, which live only
on coral reefs. Such gigantic forams, like Marginopora or Alveolinella,
reach 2-3 cm, which is an enormous size for unicellular protozoans. The
shells of most forams are perforated. Through their pores their pseudopodia
stand out. The vagile forams use them for moving, and the sessile ones for
sticking to the substrate. They also serve for collecting food and for
respiration. The foraminiferans feed on bacteria and algae, as well as on
other benthic protozoans, and on the eggs and larvae of meiobenthic
animals. The symbiotic species feed also autotrophically (Hedley 1964; Lee
1980).
The fauna of forams within a particular reef system encompasses some 40
to 120 species (Calver and Salvat 1980; Salvat and Venec-Peyre 1981; Glenn
et al. 1981). Most of them belong to two suborders: Miliolina and Rotalliina.
Miliolins have nonperforated multichamber shells. This family includes the
above-mentioned gigantic symbiotic forams Marginopora, Soritis,
Alveolinella, Peneroplis. The rotalliins have also multichamber but
Reef Zoo benthos
accumulators of carbonaceous material were accomplished by the fenestrine
bryozoans. Later in the Cenozoic, their function was taken over by the
scleractinian corals. Modern bryozoans also participate in the processes of
reef construction, being agents of consolidation of carbonaceous material.
They excrete a very sticky polysaccharide substance to glue their colonies to
the rock surfaces (Soule and Soule 1976). This glue then is quickly
impregnated by carbonate and forms a solid massive crust, which
consolidates the surfaces of rubble, and of dead corals, and thus cements the
trenches and holes in the flat and patch-reef rocks (Garrett et al. 1971;
Cuffey 1977). The branching bryozoan colonies keep and accumulate sand
and rubble in trenches and caverns participating also in the processes of
reef-rock consolidation. The material of bryozoan skeletons is a remarkable
source of carbonaceous material in bottom sediments (Cuffey 1973).
5.S Foraminifera and Other Benthic Protozoa
One of the most specific features of reef benthic communities is an extreme
abundance of foraminifera. These shelled benthic protozoans compose a
large part of the microbenthos in the soft bottom biotopes and produce over
50% of carbonaceous material of the coral sands (Renaud-Morn ant et al.
1971). The sedentary forams densely inhabit also the surfaces of rubble
material, the leaves of weeds and grasses (Glenn et al. 1981). Forams belong
to the phylum Sarcomastigophora. The cells of these protozoans live in
one-chamber or multichamber shells. The latter might contain up to 100
chambers. The shells are constructed from the chitin-like material incrusted
by calcium carbonate which the cell extracts from seawater. The size of the
shells of most forams varies usually within 0.5-1.5 mm, but some families
include one or several species of gigantic symbiotic forams, which live only
on coral reefs. Such gigantic forams, like Marginopora or Alveolinella,
reach 2-3 cm, which is an enormous size for unicellular protozoans. The
shells of most forams are perforated. Through their pores their pseudopodia
stand out. The vagile forams use them for moving, and the sessile ones for
sticking to the substrate. They also serve for collecting food and for
respiration. The foraminiferans feed on bacteria and algae, as well as on
other benthic protozoans, and on the eggs and larvae of meiobenthic
animals. The symbiotic species feed also autotrophically (Hedley 1964; Lee
1980).
The fauna of forams within a particular reef system encompasses some 40
to 120 species (Calver and Salvat 1980; Salvat and Venec-Peyre 1981; Glenn
et al. 1981). Most of them belong to two suborders: Miliolina and Rotalliina.
Miliolins have nonperforated multichamber shells. This family includes the
above-mentioned gigantic symbiotic forams Marginopora, Soritis,
Alveolinella, Peneroplis. The rotalliins have also multichamber but