Bleaching/Mortality in Vietnam

Gregor Hodgson rcgregor at
Thu Oct 22 23:06:27 EDT 1998

Report on bleaching in Vietnam.

(This updates a previous report on bleaching by Sue Wells in August.)

Coral bleaching in Vietnam has been extensive beginning in late summer
1998. In the areas off of Nha Trang (south-central Vietnam), the reefs
have experienced moderate levels of mortality in shallow water, with
Acropora being hardest hit according to Dr. Vo Si Tuan.

The conditions in the south were far worse. We resurveyed the reefs at
Con Dao National Park from 14-21 Oct. Bleaching typically affected 70%
of corals at most reefs. At most sites, 90% of the dominant
table-Acropora had been killed by mid-September and many other corals
for total losses of about 70-80% of the previous coral cover in shallow
water (1-2 m). In deeper water, the situation was equally bad in most
locations with 90% mortality of the dominant massive Porites in late
September and many other large colonies e.g. Lobophyllia. Overall coral
cover loss in deeper water was 60-70%. Hundreds of (2-3 m diameter)
massive Porites were killed including colonies as large as 9 m diameter
which are likely to be several hundred years old.

This event was a catastrophe for the national park which had been hit by
a major typhoon the previous November. Quantitative data, slides and
video will be available at ITMEMS.
Gregor Hodgson, PhD
Institute for Environment and Sustainable Development
Hong Kong University of Science and Technology
Clearwater Bay, Hong Kong
Tel: (852) 2358-8568    Fax (852) 2358-1582
Email: <rcgregor at>
Reef Check:

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