2001 summer bleaching report in Japan

Hiroya Yamano hyamano at nies.go.jp
Fri Dec 21 00:38:05 EST 2001

Dear coral listers

The International Coral Reef Research and Monitoring Center (Ministry of the
Environment, Japan, http://www.coremoc.go.jp/english/top_e.html) and the
Japanese Coral Reef Society summarized the bleaching status around Japan in
the summer of 2001.

---Summary Report---

Overview: Due to high water temperature in July and August, bleaching in
corals and soft corals was observed in the Ryukyu Islands (from Yaeyama
Islands to Yaku Island), while no significant bleaching was observed at
around Japan Main Islands and Ogasawara Islands. In September, typhoons
struck the Ryukyu Islands and reduced the water temperature, resulting in
the end of the bleaching.

1. Ryukyu Islands
1-1. Yaeyama Islands (24.4N, 124E)
*Water temperature
Water temperature reached >30 degC in late-June and early-July, and kept
30-31 degC till late August. The temperature suddenly dropped into 28-29
degC in September due to an approach of a typhoon.
*Bleaching status
Pale or partially-bleached corals were first observed in early- to mid-July.
The bleaching spread throughout the area in late-July to mid-August. Severe
bleaching was observed in late-August. A loss of 70-80% of healthy Acropora
and dead Seriatopora covered with algae were found. The bleaching ended in
September. At that time, some corals were found to be recovered.

1-2. Miyako Island (24.7N, 125.4E)
*Water temperature
Water temperature reached >30 degC from late-June, and kept around 30 degC
from early-July to early-August with minor daily fluctuations.
*Bleaching status
Pale or partially-bleached corals were observed from June to August, but not
so severe. The bleaching ended in late September.

1-3. Okinawa Island (26.5N, 128E)
*Water temperature
Water temperature increased to reach 29 degC in June at a depth of up to 30
m. It was over 30 degC in dairy average from mid-July to mid-August. In mid-
and late-August, the temperature began to decrease. Typhoons struck Okinawa
in September, and temperature decreased significantly.
*Bleaching status
Initial bleaching was found in late-July at shallow areas in Acropora.
Bleaching was commonly observed from late-July to early-August in Acropora,
Pocillopora and Montipora, but completely bleached corals were rare. The
bleaching ended in September.

1-4. Amami Islands (28.2N, 129.4E)
*Water temperature
Water temperature was ~30 degC in mid-August. The temperature decreased
after mid-August when a typhoon struck the island.
*Bleaching status
Initial bleaching was observed in late-July at shallow reefs flats and
backreef moats.
In August, complete bleaching was observed in Porites that survived in the
1998 bleaching, in Acropora that recruited after the 1998 bleaching, and in
50 % of transplanted corals after the 1998 bleaching.

1-5. Yaku Island (30.3N, 130.5E)
*Water temperature
Water temperature in the daytime was 30~32 degC from late-July to
early-August. The daytime temperature was <30 degC in mid- and late-August
and dropped into 28 degC in September.
*Bleaching status
Bleaching was observed from late-July to early August in Acropora that
recruited after the 1998 bleaching, in sea anemones, and in soft corals. Sea
anemones was recovering from the bleaching in early-October.

2. Japan Main Islands
2-1. Amakusa, Kyushu (32.2N, 130E)
No significant bleaching was observed.

2-2. Kushimoto (33.5N, 135.8E)
Slight coral bleaching was found only in a tide pool. No significant
bleaching in other places.

3. Ogasawara Islands (27N, 142.2E)
No significant bleaching was observed.

 >>(#(">              --- Hiroya Yamano, Dr. ---
     <")=)<<  Social and Environmental Systems Division
 Y            National Institute for Environmental Studies
_Y_Y__Y_  16-2 Onogawa, Tsukuba, Ibaraki, Japan

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