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International Journal of Marine Science 2013, Vol.3, No.4, 23-32
http://ijms.sophiapublisher.com
26
The settlements mostly consisted of
Acropora
(4~5 species),
Millepora
(2 species),
Porites
(3 species)
and few species of
Goniopora
,
Galaxea
,
Symphyllia
,
Mycedium
,
Goniastrea
,
Leptastrea
,
Montipora
,
Stylophora
,
Pocillopora
and
Turbinaria
genera.
Sometimes individual colonies of alcyonarians and
gorgonarians occurred. Sparse bivalves and
gastropods (
A. vexillum
,
M. malleus
,
Pteria penguin
,
Chicoreus ramosus
,
Ch. microphyllus
),
sea lilies and
some other invertebrates were recorded in the
associated fauna.
The west–east transect. At the beginning of the
transect oriented from the shore to the open sea, at
depth of 4.5 m, an extended area of scrap of dead
corals was observed. Small, up to 10 cm diameter,
individual colonies of
Pocillopora, Stylophora,
Acropora (A. palifera, A. humilis, A. millepora,
and
A.
florida), Montipora, Porites, Leptoria, Platygyra,
Pavona, Hydnopohora, Favia
, and
Favites
occurred
for the next 50 m. The projective coral covering of
bottom was 10%~15%. There were also numerous
dead lamellar colonies of
Acropora
up to 2 m in size.
Between the 140th and 150th meter of the transect
Stylophora pistillata
dominated among corals in its
frequency of occurrence. Further, the zone of
settlements of
Acropora
,
Porites
and the alga
Chnoospora
was spread; the projective cover of the
bottom was about 75%. The scleractinian habitus
showed that they were under attack by the sea star
Acantaster planci
,
whose population density reached
5~7 ind/m
2
.
Concurrently with
A. planci
the gastropod
Charonia
tritonis
, the bivalves
T. squamosa
, and relatively
young
T. crocea
occasionally occurred there. At a
distance of 200~400 m from the beginning of the
transect the settlements of
Acropora
were still spread,
however, the settlements of
A. formosa
,
A. cytherea
,
and
A. hyacinthus
were the most common there.
Among
Acropora
settlements, more often than
previously, bottom areas with dead corals and their
fragments, which were more or less covered with the
calcareous algae
Amphizoa
,
Halimeda
, and
Hyphnea
panosa
occurred. With the 430th meter of the transect
Acropora
settlements acquired a distinctly patched
pattern, and the percentage of projective cover of the
bottom varied from 40 up to 80%. In that zone as a
whole, concurrently with
Acropora
, individual
colonies of
Favia
,
Favites
,
Montipora
,
Porites
and
Heliopora
were widespread. Starting from the 450th
meter of transect, the extended buttress system area
began at a depth of 10 m, comparable to that of the
south reef area. It specified by the same set of growth
forms and a similar species composition of corals and
associated fauna. The zone was traced along the
transect up to the 520th meter, then the number of
corals and diversity of their growth forms decreased
on the reef slope. Massive and encrusting forms
dominated and occasional small bioherms occurred.
The projective cover of the bottom did not exceed
12%~15%. A further increase in depth up to 14 m was
associated with strong silting of the bottom and an
increase in water turbidity. Only occasionally, after the
570th meter of transect, was it possible feel a small
colony of coral by hand.
1.2 Reef of Re Island
Transect from the southwest to the northeast side of
the reef (Figure 4). At a depth of 25 m, on the fore reef
platform with slightly silted sand sediments with
detached boulders and spalls of dead coral, isolated
colonies
of
alcyonarian,
gorgonarians
and
scleractinian occurred. A gradual decrease in depth
observed to the northeast for 200 m of transects. The
number of coral colonies significantly increased along
with an increase in their size.
Sinularia dura
,
Sarcophyton sp.
,
Porites lobata
,
Isopora palifera
,
Pocillopora verrucosa
, and
Montipora venosa
were
the most common corals. The coral covering of the
substrate did not exceed 5%~7%. At a depth of 12 m,
bioherms from 0.9 up to 2.5 m high and up to 1.5~4 m
in diameter were common. They consisted of
polyspecies settlements of alcyonarian and
scleractinian, in which
Sinularia
,
Porites
,
Favia
and
Favites
prevailed. The first dominated by substrate
cover, up to 30%, the rest by number species up to
7~9. The scleractinian of the Euphyllidae,
Meruliniidae, and Mussidae families (by 2~3 species)
and individual colonies of
Acropora
,
Montipora
,
Astreopora
,
Pocillopora
, and
Seriatopora
occurred in
that part of the reef rather often. Sponges, bivalves,
gastropods and the sea urchin were characteristic in
the associated invertebrate fauna for the area (see
Table 2). Shrubs of the macrophytes
Asparagopsis
taxiformis
,
Padina australis
,
Caulerpa racemosa
,
Amphiroa fragilissima
, and
Halimeda
sp. The
composition of the fauna of reef slopes also had high