ISSN 1063-0740, Russian Journal of Marine Biology, 2008, Vol. 34, No. 4, pp. 199–219. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © E.A.Titlyanov, T.V. Titlyanova, 2008, published in Biologiya Morya.
There are several reviews devoted to the description
of algae and coral interrelation on coral reefs. Thus,
Miller  analyzes the effects of local and latitudinal
external factors on competitive interrelations between
sea algae and corals and on the composition and struc-
ture of reef ecosystem communities. McCook 
described the competitive interrelation of algae and
corals on adverse and degenerating coral reefs of Aus-
tralia. In a paper by McCook  the mechanisms of
competition of algae and corals for space, substrate,
nutrient resources, and for the conditions needed for
successful competitive activities of algae with corals
and vice versa were discussed.
In our review we discuss some data on the competi-
tive interrelation of algae and corals on reefs that have
been damaged as the result of natural and anthropo-
genic catastrophes, from the ﬁrst days of the damage to
their restoration or complete degradation.
Natural and Anthropogenic Catastrophes
on Coral Reefs
During the last decades of the previous century and
in the beginning of the current one coral reefs of the
World Ocean have undergone catastrophic changes
under the inﬂuences of natural and anthropogenic fac-
tors [21, 23, 50, 52, 61, 110, 119, 151, 152, 157, 158].
In the shallow areas of tropical and subtropical zones of
the World Ocean at the present time up to 80% of her-
matypic coral populations have been lost, and together
with them other animals, which are coral symbionts or
coral reef associates [38, 39, 67, 79] (ﬁgure, A and B).
The main cause of coral reef loss is the 1–2
temperature increase in the tropical and subtropical
zones of the World Ocean in comparison with the
monthly mean temperature within the hot season [61,
81, 89], which is probably caused by such global cli-
matic changes as warming [21, 120, 156], and the El
Nino effect [37, 53, 54, 127]. Coral loss upon a water
temperature increase occurs due to disruption of the
symbiotic relation between animals-polyps and their
endosymbiotic algae-zooxanthellae, resulting in coral
bleaching and degradation of host cells, or in being
extruded [27-29, 106, 135, 142,]. Thus, corals exposed
to elevated temperatures bleach partially or completely,
and may be lost in the future. In some cases due to the
long-term effects of high temperature (1–2 months) all
coral can be lost in shallow waters [35, 88].
In 1998 the greatest coral bleaching of the century
took place [125, 158], which affected almost all the
coral reefs of the Indo-Paciﬁc [24, 48, 110] (ﬁgure, A
and B) and partially of the Atlantic [22, 54].
Coral–Algal Competition on Damaged Reefs
E. A.Titlyanov and T. V. Titlyanova
A.V. Zhirmunsky Institute of Marine Biology FEB RAS, Vladivostok, 690041 Russia
Accepted: January 31, 2008
—Natural and anthropogenic catastrophes occurred at the end of the previous and in the beginning of
the current centuries at the coral reefs of the World Ocean, and their consequences for the tropical shelf ecosys-
tems have been described based on published data and our own investigations. It has been shown that in recent
decades coral populations on reefs of tropical and subtropical regions of the World Ocean have been reduced
by 80%, and in some areas have completely vanished. The biodiversity of reef ecosystems has been consider-
ably reduced. The main reason for such changes is a1–2
C increase in the temperature of surface waters in com-
parison with the monthly mean temperature in the hot season. The fate of the damaged coral reefs is under dis-
cussion. It is thought that in clean waters partially damaged coral reefs can recover, whereas in waters polluted
as the result of human activity they collapse. The rate of coral reef restoration depends on the hydrological and
hydrochemical conditions, frequency of natural calamities and competitive interrelation of algae and corals on
the damaged sites of coral reefs. The nature of competitive interrelation between algae and corals is considered,
viz., the dynamics of obliteration of damaged and dead coral colonies by various algal species, mechanisms of
competitive interrelation, effects of the environment on the competitive ability of corals and algae, the internal
and external conditions for victory in competitive activity. It has been suggested that coral reefs can be restored
through temporary transformation into a vegetable reef. In the absence of natural calamities damaged reefs can
be clearly restored to their original or altered state over several decades, but only in clean waters.
algae, corals, competition, natural and anthropogenic catastrophes.