208
Reef Zoobenthos
living cells of zooxanthellae, we have concluded that they assimilate 14C02
in the light: after 1 h of exposure to light the radioactivity of 14C consumed
was 15 cpm x 10 2 cells, and in the dark only 4 cpm.
5.9 Insects
Among the bottom fauna of the coastal shallows and of the biotopes of reef
flats covered with seaweeds the larvae of mosquitoes - chironomids - and
the larvae of butterflies are often present. Their number may attain several
thousands per m 2 (Robles and Cubit 1981; Cheng 1985). On exposed rocky
surfaces of reef flats and of littoral areas the sea bugs Aepophilis and
Omania, as well as the beetles Hyphalus could be met with (Britton 1971;
Cheng 1976). In the surface film over the reef shallows the beetles waterglider Halobates and water-tiger Corixis are usually numerous (Chieng
1985). These insects and their larvae may play a significant role in the
trophodynamics of the shallow's reef habitats, but data in this field are still
scarce (Chieng 1985).
5.10 Distribution, Communities Structure and Abundance
The bottom fauna of coral reefs is characterized by a high degree of specific
variability. It is especially varied in biotopes of the rocky flat and of the
outer slope. This proves the truth of the statement that one of the main
factors causing this high variability in reef fauna is the abundance of refuges
which prevent grazing (Kohn and Levitien 1976). The most abundant and
various benthic fauna was recorded usually in cavernous reef-flats perforated
by numerous burrows and holes, and covered with stones and rubble
(Sirenko 1980). The second important factor that controls the abundance of
fauna is trophic conditions. Both these factors are optimal in the areas of
reef flats covered with seaweeds and periphyton that are not exposed at low
tide (Bakus 1969). The degree of species diversity within separate families
appears to be inversely proportional to the density of their specific
populations in reef biotopes. For example, in dense communities of Conidae
in rocky littoral zones the species diversity was much less than in those in
the biotopes of reef flats where the density of these gastropods was one
order less (Kohn 1968).
The total number of species of macrobenthos (excluding corals) counted
within a particular reef system varied within 250-500. But in fact it could
be much more because a significant portion of the cryptofauna is underestimated. In reef benthic communities their individual groups occupy all
possible econiches and use all possible sources of food: plankton, suspended
Reef Zoobenthos
living cells of zooxanthellae, we have concluded that they assimilate 14C02
in the light: after 1 h of exposure to light the radioactivity of 14C consumed
was 15 cpm x 10 2 cells, and in the dark only 4 cpm.
5.9 Insects
Among the bottom fauna of the coastal shallows and of the biotopes of reef
flats covered with seaweeds the larvae of mosquitoes - chironomids - and
the larvae of butterflies are often present. Their number may attain several
thousands per m 2 (Robles and Cubit 1981; Cheng 1985). On exposed rocky
surfaces of reef flats and of littoral areas the sea bugs Aepophilis and
Omania, as well as the beetles Hyphalus could be met with (Britton 1971;
Cheng 1976). In the surface film over the reef shallows the beetles waterglider Halobates and water-tiger Corixis are usually numerous (Chieng
1985). These insects and their larvae may play a significant role in the
trophodynamics of the shallow's reef habitats, but data in this field are still
scarce (Chieng 1985).
5.10 Distribution, Communities Structure and Abundance
The bottom fauna of coral reefs is characterized by a high degree of specific
variability. It is especially varied in biotopes of the rocky flat and of the
outer slope. This proves the truth of the statement that one of the main
factors causing this high variability in reef fauna is the abundance of refuges
which prevent grazing (Kohn and Levitien 1976). The most abundant and
various benthic fauna was recorded usually in cavernous reef-flats perforated
by numerous burrows and holes, and covered with stones and rubble
(Sirenko 1980). The second important factor that controls the abundance of
fauna is trophic conditions. Both these factors are optimal in the areas of
reef flats covered with seaweeds and periphyton that are not exposed at low
tide (Bakus 1969). The degree of species diversity within separate families
appears to be inversely proportional to the density of their specific
populations in reef biotopes. For example, in dense communities of Conidae
in rocky littoral zones the species diversity was much less than in those in
the biotopes of reef flats where the density of these gastropods was one
order less (Kohn 1968).
The total number of species of macrobenthos (excluding corals) counted
within a particular reef system varied within 250-500. But in fact it could
be much more because a significant portion of the cryptofauna is underestimated. In reef benthic communities their individual groups occupy all
possible econiches and use all possible sources of food: plankton, suspended