11 Destruction and Recovery of Reef Systems,
Reef and Man
Coral reef ecosystems, as also the ecosystems of tropical rain forests, are
among the most mature ecosystems on our planet. Such mature ecosystems
are very sensitive to external impacts, be they natural or manmade, which
violate their homeostasis. During the last three decades, catastrophic events
affected coral reef systems, resulting in their destruction in vast areas;
hurricanes, the warming of water by the El Niiio, cuuurent extra low tides,
Acanthaster plagues, and various kinds of anthropogenic stress were among
the causes. The regeneration of thus degraded reef ecosystems takes
decades. The close interconnection and cumulative effect of the natural and
anthropogenic stress factors in processes of destruction of the reef systems
caused by them appears to be clearer and clearer. For example, in polluted
reef areas corals are much more exposed to the attacks of boring sponges
and so they can be destroyed easier by waves. A definite causal connection
between human activity and the Acanthaster outbreaks is also assumed.
11.1 The Acanthaster Problem
The "crown of thorns" sea-star Acanthaster planci is a large specialized
corrallovore asteroid, which feeds exclusively on scleractinian corals.
Massive infestations were first recorded in the early 1960s at some of the
Indo-Pacific reefs (Barnes and Endean 1964; Barnes, 1966 Chesher 1969;
Kuhlmann 1971; Endean and Stablum 1973). They resulted in the
catastrophic degradation of the latter. The number of reef sites infested and
damaged by this star plague till the end of the 1970s drastically increased
(Talbot and Talbot 1971). At the beginning of the 1980s many of the
previous deteriorated and in part also recovered reefs experienced
repetitions of the Acanthaster invasions (Moran, 1986). At reefs attacked by
hordes of these stars 50 to 90% of scleractinian corals die. The subsequent
recovery might take 10-40 years, depending on the degree of damage and
on not being attacked by stars repeatedly. But events on reefs of the GBR
region, which had been damaged earlier by Acanthaster in 1960-1969
indicated the possibility of repetition of attacks. This implies the threat of
Reef and Man
Coral reef ecosystems, as also the ecosystems of tropical rain forests, are
among the most mature ecosystems on our planet. Such mature ecosystems
are very sensitive to external impacts, be they natural or manmade, which
violate their homeostasis. During the last three decades, catastrophic events
affected coral reef systems, resulting in their destruction in vast areas;
hurricanes, the warming of water by the El Niiio, cuuurent extra low tides,
Acanthaster plagues, and various kinds of anthropogenic stress were among
the causes. The regeneration of thus degraded reef ecosystems takes
decades. The close interconnection and cumulative effect of the natural and
anthropogenic stress factors in processes of destruction of the reef systems
caused by them appears to be clearer and clearer. For example, in polluted
reef areas corals are much more exposed to the attacks of boring sponges
and so they can be destroyed easier by waves. A definite causal connection
between human activity and the Acanthaster outbreaks is also assumed.
11.1 The Acanthaster Problem
The "crown of thorns" sea-star Acanthaster planci is a large specialized
corrallovore asteroid, which feeds exclusively on scleractinian corals.
Massive infestations were first recorded in the early 1960s at some of the
Indo-Pacific reefs (Barnes and Endean 1964; Barnes, 1966 Chesher 1969;
Kuhlmann 1971; Endean and Stablum 1973). They resulted in the
catastrophic degradation of the latter. The number of reef sites infested and
damaged by this star plague till the end of the 1970s drastically increased
(Talbot and Talbot 1971). At the beginning of the 1980s many of the
previous deteriorated and in part also recovered reefs experienced
repetitions of the Acanthaster invasions (Moran, 1986). At reefs attacked by
hordes of these stars 50 to 90% of scleractinian corals die. The subsequent
recovery might take 10-40 years, depending on the degree of damage and
on not being attacked by stars repeatedly. But events on reefs of the GBR
region, which had been damaged earlier by Acanthaster in 1960-1969
indicated the possibility of repetition of attacks. This implies the threat of