Status of Coral Reefs of the World 2000

Status of Coral Reefs of the World: 2000
coral communities had less than 5% cover. On Ishigaki Island moats (Yaeyama Islands),
coral communities had less than 5% coral cover, whereas cover was much higher in some
communities on the east and northwest side. Sekisei lagoon between Ishigaki and Iriomote
Islands, has over 13,000ha of coral communities with 9.9% having over 50% cover, mostly
in the north of the lagoon.
The reef margins in the Nansei Islands (surveyed with 1,300km of manta tows) had 52%
coral cover ranging from as low as 5%, with the margins higher percentages than the moats.
On the main island of Okinawa, 67% of the reef margins had coral cover less than 5%,
whereas in the nearby Kerama Islands, most coral communities had high coral cover. There
are many seagrass beds in the Ryukyu Islands, estimated at 6,900ha, and smaller ones
around Amami Islands (130ha). The largest area of seagrass beds was in Yaeyama Islands
(approx. 60% of the Ryukyu Islands) and on the east coast of Iriomote Island, seagrass beds
covered 1,400ha.
The most severe coral bleaching and mortality event ever observed occurred around
southern Japan during the summer of 1998, where 97 municipalities reported bleaching
from: the Ryukyu Islands to Hachijo Island south of Tokyo; to the Amami Islands; southern
Kyushu; Shikoku; and southern Honshu. No bleaching was observed in western Shikoku,
Miyake Island or Ogasawara Islands in the Kuroshio region. Reported bleaching was 40-60%
in Nansei Island; under 20%, in Koshikijima Island western Kyushu, eastern Shikoku and
Kushimoto; 30-40% on Hachijo Island (most severe was 80-90% on Hachijo Island).
Mortality was 70-90% on south Yoron Island and 30-60 % on north Yoron Island. Surveys
before and after the bleaching in the Sekisei Lagoon, showed that 40% of Acropora died
after bleaching and 8% of all coral cover was lost. In Ishigaki Island, coral cover showed a 62%
decrease after bleaching, with the most damaged corals being Acropora. Whereas mortality in
Heliopora coerulea, Porites cylindrica and branching Montipora was not significant.
Taiwan
Due to coastal development and pollution, there has been substantial degradation to some
reefs during the past 10 years, with living coral cover being reduced from approximately
50% to 30% and some species of reef fishes, gastropods, and crustaceans becoming
locally extinct. Destructive fishing practices (especially dynamite), sedimentation from
construction and dredging, coral collection, sewage pollution, aquarium fish collecting,
and unregulated tourist activities have caused this damage.
Reefs in the Penghu Islands (west of Taiwan on the Tropic of Cancer) have been extensively
damaged by dynamite fishing, trawling, and sedimentation. The Lutao and Lanyu reefs
(southeast of Taiwan) are being damaged by destructive fishing practices and intensive
tourist activities. Reef fish populations are very low because of aquarium fish collecting and
spearfishing. In 1998, extensive coral bleaching occurred on the reefs in southern Taiwan,
Penghu Islands, Lutao, and Lanyu, with approximately 30% to 50% of coral colonies
bleached. Surveys in 1999 and 2000 revealed that about 20% of coral colonies had died
during this bleaching event.
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