160
Benthic Microflora, Periphyton and Plant Associations
total, but on the "algal reefs" with a weak coral growth or at high-latitude
reefs it could be up to 70-80%. Their most important ecological feature is a
high net primary production as compared with other primary producers, like
corals. The PIM ratios in plant associations are most often 2 to 4, while in
associations dominated by corals it is close to 1.5-2 (see Tables 4.18,4.19).
From this point of view benthic plant communites are among the main
suppliers of reef ecosystems with primary organic matter. This role is
especially important in biotopes of lagoons and reef-flats. The function of
calcareous algae as reef builders was discussed above (d. Sect. 1.2).
The ecological role of reef plant associations is greatly enhanced by the
domination of mini-thallomic or filamentous macrophytes and seagrasses in
them, which are readily consumed and digested by herbivores (Ott and
Mauer 1977). The same high trophic quality is possessed by numerous
epiphytic and epilithic algae, as well as by coralline algae (d. Sects. 5.6,
6.3.1). The direct grazing of a significant part (20-40% of total primary
production created within the reef ecosystems) shortens and simplifies the
food-chain, incrasing thus the efficiency of secondary production processes
(Randall 1967; Bakus 1969). The apparent abundance of herbivorous fish
and invertebrates in reef benthic communities is one of the main factors
responsible for their unusually high density in bottom biotopes. On the
other hand, a high grazing pressure, resulting in the cleaning of solid reef
substrates from plants occupation, makes to a large extent their colonization
possible by sessile reef-building organisms, including coralline algae (Bakus
1969; Littler and Doty 1975; Birkeland 1977; Wanders 1977; Hatcher
1983b).
Reef benthic plants are a main source of food for about a quarter of the
species of reef fish (Earle 1972). Out of 212 species of reef fish off the
Antilles, in 59 plants comprised a significant part of their food rations. Many
fish feed on plant detritus. Among the herbivorous invertebrates there are
many species of gastropods, urchins, crabs, and shrimps (Klumpp and
Pulfrich 1989). A number of fish, as well as urchins and green turtles, feed
on seagrasses, or on detritus produced by their dead leaves (Zieman 1975;
Ogden and Zieman 1977; Ogden et al. 1980). Through the detritus food
web, the production by mangroves is also incorporated into reefal
trophodynamic processes (Lugo and Snedeaker 1974; Teas 1983).
Benthic Microflora, Periphyton and Plant Associations
total, but on the "algal reefs" with a weak coral growth or at high-latitude
reefs it could be up to 70-80%. Their most important ecological feature is a
high net primary production as compared with other primary producers, like
corals. The PIM ratios in plant associations are most often 2 to 4, while in
associations dominated by corals it is close to 1.5-2 (see Tables 4.18,4.19).
From this point of view benthic plant communites are among the main
suppliers of reef ecosystems with primary organic matter. This role is
especially important in biotopes of lagoons and reef-flats. The function of
calcareous algae as reef builders was discussed above (d. Sect. 1.2).
The ecological role of reef plant associations is greatly enhanced by the
domination of mini-thallomic or filamentous macrophytes and seagrasses in
them, which are readily consumed and digested by herbivores (Ott and
Mauer 1977). The same high trophic quality is possessed by numerous
epiphytic and epilithic algae, as well as by coralline algae (d. Sects. 5.6,
6.3.1). The direct grazing of a significant part (20-40% of total primary
production created within the reef ecosystems) shortens and simplifies the
food-chain, incrasing thus the efficiency of secondary production processes
(Randall 1967; Bakus 1969). The apparent abundance of herbivorous fish
and invertebrates in reef benthic communities is one of the main factors
responsible for their unusually high density in bottom biotopes. On the
other hand, a high grazing pressure, resulting in the cleaning of solid reef
substrates from plants occupation, makes to a large extent their colonization
possible by sessile reef-building organisms, including coralline algae (Bakus
1969; Littler and Doty 1975; Birkeland 1977; Wanders 1977; Hatcher
1983b).
Reef benthic plants are a main source of food for about a quarter of the
species of reef fish (Earle 1972). Out of 212 species of reef fish off the
Antilles, in 59 plants comprised a significant part of their food rations. Many
fish feed on plant detritus. Among the herbivorous invertebrates there are
many species of gastropods, urchins, crabs, and shrimps (Klumpp and
Pulfrich 1989). A number of fish, as well as urchins and green turtles, feed
on seagrasses, or on detritus produced by their dead leaves (Zieman 1975;
Ogden and Zieman 1977; Ogden et al. 1980). Through the detritus food
web, the production by mangroves is also incorporated into reefal
trophodynamic processes (Lugo and Snedeaker 1974; Teas 1983).