Basic HTML Version
International Journal of Marine Science 2014, Vol.4, No.39: 1-4
http://ijms.biopublisher.ca
2
Figure 4 Different stages of development of a coral reef. A,
superficial layer of corals on a solid substratum. B, Primary
framework stage. C, Young fringing reef with formative
zonation. D, Structural reef with clear zonation. (a, lagoon; b,
reef flat; c, reef slope ( by Latypov, 1995)
Coral community characteristics
Along the coast, for a distance of 20-40 m and at a
depth to 1 m, occurs an algal-coral zone dominated by
macrophytes i.e.,
Sargassum, Padina, Asparagopsis
and
Turbinaria
, crusts of the zoanthid
Palythoa
and
individual small massive and encrusting colonies of
the scleractinian
Porites, Leptoria, Goniastrea,
Pavona
and
Hydnophora
. The substratum covered
with algae for no more than 10% (rarely 40% in some
areas) with
Sargassum polycystum
or
Asparagopsis
taxiformis
dominant. Corals cover between 7-15% of
the substratum with
Galaxea fascicularis
,
Leptastrea
transversa
and
Porites lobata
dominant, the latter
forming flat microatolls up to 1.5 m across. At 40-60
m off the coast and with increasing depth to 2 m, the
numbers and abundance of scleractinian increase. The
degree of substratum covered with corals reaches 40%
with
P. lobata, G. fascicularis
and
Pavona decussata
dominant.
Between 70-80 m offshore, the bottom drops from
three to 9-11 m. The depth change occurs either
gradually or by two to three sharp steps. An associated
change takes place in species composition and pattern
of coral settlement on the reef slope. Large (up to 2 m
across) colonies of
Galaxea, Lobophyllia
, plate-like
Acropora, Montipora
, and plate-like encrusting
Echinopora, Echinophyllia, Mycedium, Pachyseris
and the lamellar-funnel form of
Turbinaria
are
dominant. Massive colonies of
Porites
occur on the
upper and middle parts of the reef slope (1.5-2 m in
height). Species richness increases two fold. The
degree of coral covers in creases to between 70-80%
and to 100% in places with large colonies of
G.
fascicularis, Acropora cytherea
and
Lobophyllia
hemprichii
. The reef slope community is divided
distinctly into two facies, i.e.,
Acropora cytherea +
Galaxea fascicularis
on the upper part of the reef
slope and
Cladiella sp.+Lobophyllia hemprichii
on the
lower. Towards the base of the reef slope (to a depth of
between 8-10 m) scleractinian richness and individual
numbers decreased. The genera
Goniopora,
Lobophyllia, Podobacia, Echinopora, Oxypora,
Pectinia
and
Turbinaria,
were most common here as
individual colonies covering between 3-5% of the
substratum surface.
3 Discussion
Zonal morphological differences, the specificity of
species composition of scleractinian, and the coral
structures of Socotra Island and most of the reefs of
the Baitylong archipelago do not have zones typical
for reefs of other Indo-Pacific regions such as lagoons,
reef flat, etc. At many the investigated profiles,
polyspecific specialized settlements, notably the
common crusted forms, are developed. Colonies of
S.
pistillata
, one of the pioneer settlements of reefs,
universally distributed in relatively large numbers.
Coral settlements represented in the form of a weak
covering layer only slightly changing the morphology
of the underwater slope (Hubbard, 1974; Dai, 1993;
Latypov, 1995; Kosmynin et al., 1982; Latypov, 2003,
2011). The carbonaceous body of the possible future
reef starts to form in zone of bioherms where large
colonies grouped with bioherms. All this indicates that
the coral structures of Socotra Island are in the middle
stage of development of the contiguous reefs usually
forming on the sloping substrate (Dai, 1993; Latypov,
1995).The present reef structures of Socotra Island