Feeding of Reef Fish
237
1974). These fish bite off the tips of coral branches and scrape coenosarc
from the colonies of massive corals together with calcareous material. The
balistid Alutera scripta and some chaltodontids graze also the octocorals.
Among fish of the second trophic group feeding on vagile benthos with
firm outer skeleton there could be mentioned the ray Aetobatus narinari,
the grunters Haemulon plumeri, H. macrostomus, the wrasses (genera
Bodianus, Halicoeres, Hemipteronotus, Thalassoma) , the balistid Balistes
vetula, the box fish Lactophris trigon us , most tetraododontids, diodontids
and ogcocephalids. They have massive craniums and jaws. Thus they are
able to crush the testes of crabs, urchins and sea stars, the shells of
gastropods and chitons with the aid of their jaws and throat teeth. The
smaller vagile macro- and meiobenthos are consumed by rays, sand sharks,
moray eels, holocentrids, by many groupers (genera Aphestes, Cephalopholis, Epinephelus, Myctoperca, Pterometopon) , by wrasses (genera
Bodjanus, Halicoeres, Talassoma), by some cerrithids and grunters (genera
Haemulon, A nisotrem us , Rhonciscus, Macolor) , by pomacentrids (Pomacentrus planifrons, P. partitus) , by goatfish, flDunders (genera Botus, Achirus) ,
by some chaetodontids, scorpion fish, and box fish (Lactophrys triqueter).
Main components of their food ration are polychaetes, shrimps and small
crabs, which comprise over 70% of their gut contents (Table 6.13). The
total amount of ash-free food material consumed by this group of fish per
day attains on reef fiats 2-3 g m -2, and in lagoons 0.5 g m -2. Thus these
benthic fish graze out the bulk of primary and secondary production of
bottom biotopes (Hatcher 1981).
The guild of piscivorous predatory fish includes 10-20% of the total
number of species of reef ichthyofauna (Tables 6.10, 6.12). These numbers
are only tentative because the fish, and especially their young and larvae,
compose a significant part of food ration also in many benthovorous and
planktovorous fish (Randall 1967). The share of fish as a food in the total
food ration of reef fish communities varies in different reef zones: from 5%
in the lagoon up to 20% on the reef slope (Fig. 6.3). The biomass of
obligate predatory fish usually does not exceed 5 -10%. Among the latter
the most numerous are groupers, caranxes, moray eels, barracudas,
emperors (fam. Lethrinidae). This group inludes also some Iutjanids
(Lutjanus cyanopercus) , mackerels (genus Scomberonorus) , belonids,
aulostomids and fistulariids, snake eels, synodontids, and reef sharks
(genera Carcharhinidae, Orectolobidae). Besides fish prey the obligate
piscivores hunt cephalopods - squids, octopuses, cattle fish, and shrimps and
crabs. The grazing activity of predatory fish is an important factor
controlling the composition and the density of fish communities (Sale 1980;
Talbot et al. 1978).
237
1974). These fish bite off the tips of coral branches and scrape coenosarc
from the colonies of massive corals together with calcareous material. The
balistid Alutera scripta and some chaltodontids graze also the octocorals.
Among fish of the second trophic group feeding on vagile benthos with
firm outer skeleton there could be mentioned the ray Aetobatus narinari,
the grunters Haemulon plumeri, H. macrostomus, the wrasses (genera
Bodianus, Halicoeres, Hemipteronotus, Thalassoma) , the balistid Balistes
vetula, the box fish Lactophris trigon us , most tetraododontids, diodontids
and ogcocephalids. They have massive craniums and jaws. Thus they are
able to crush the testes of crabs, urchins and sea stars, the shells of
gastropods and chitons with the aid of their jaws and throat teeth. The
smaller vagile macro- and meiobenthos are consumed by rays, sand sharks,
moray eels, holocentrids, by many groupers (genera Aphestes, Cephalopholis, Epinephelus, Myctoperca, Pterometopon) , by wrasses (genera
Bodjanus, Halicoeres, Talassoma), by some cerrithids and grunters (genera
Haemulon, A nisotrem us , Rhonciscus, Macolor) , by pomacentrids (Pomacentrus planifrons, P. partitus) , by goatfish, flDunders (genera Botus, Achirus) ,
by some chaetodontids, scorpion fish, and box fish (Lactophrys triqueter).
Main components of their food ration are polychaetes, shrimps and small
crabs, which comprise over 70% of their gut contents (Table 6.13). The
total amount of ash-free food material consumed by this group of fish per
day attains on reef fiats 2-3 g m -2, and in lagoons 0.5 g m -2. Thus these
benthic fish graze out the bulk of primary and secondary production of
bottom biotopes (Hatcher 1981).
The guild of piscivorous predatory fish includes 10-20% of the total
number of species of reef ichthyofauna (Tables 6.10, 6.12). These numbers
are only tentative because the fish, and especially their young and larvae,
compose a significant part of food ration also in many benthovorous and
planktovorous fish (Randall 1967). The share of fish as a food in the total
food ration of reef fish communities varies in different reef zones: from 5%
in the lagoon up to 20% on the reef slope (Fig. 6.3). The biomass of
obligate predatory fish usually does not exceed 5 -10%. Among the latter
the most numerous are groupers, caranxes, moray eels, barracudas,
emperors (fam. Lethrinidae). This group inludes also some Iutjanids
(Lutjanus cyanopercus) , mackerels (genus Scomberonorus) , belonids,
aulostomids and fistulariids, snake eels, synodontids, and reef sharks
(genera Carcharhinidae, Orectolobidae). Besides fish prey the obligate
piscivores hunt cephalopods - squids, octopuses, cattle fish, and shrimps and
crabs. The grazing activity of predatory fish is an important factor
controlling the composition and the density of fish communities (Sale 1980;
Talbot et al. 1978).