[Coral-List] Mystery Event - Lankayan Island, Sulu Sea Sandakan

Chung, F.C. achier300 at yahoo.com
Sun Aug 26 06:10:33 EDT 2007

Dear all,

The mortality of shallow corals on reef flat at Lankayan Island few months (January
2007) back were duel to input of river water from mainland. I was on the island
to witness the changes of the water quality during the event. Lankayan
 Islands is located about 26 Kilometers
away from the mainland. In last January, rough sea and unusual rain
fall had caused flooded in few places near Sandakan.
The inputs of river water to Lankayan were observed continuously more than 10
days bringing debris like bamboo, Rhizophora seeds, sargassum mat. Water colour
changing from clear to greenish and then to brownish (day 10). After 11 days, dead
sea cucumbers and sea urchins were washed ashore, giant clams fleshes were
floating on surface. The brown water colour was first observed in Lankayan and
it had suspected contents harmful substance from river that possible killing
the coral, giant clam and etc. However no laboratory test was done on the water
that time. 


Basic water quality parameters were measured during the
event, we found that the water salinity was low (average 25ppt, minimum 17 ppt)
on both surface and in 5 m. Average water temperature was 27.8C and no dead
fish was observed during the event. On day 12, we did a survey dive, the water
colour was green but clear and water temperature around 27C. The shallow coral
from 4m and above were death, majority Acropora
sp, Seriatopora sp, blue coral and others. A short paper regarding these
phenomena is in press. Click on link below to see photographs taken during the event.





Achier/ Chung Fung Chen

Marine Biologist

Reef Guardian Sdn Bhd

Lankayan Island

Sugud Islands
Marine Conservation Area (SIMCA)

Sandakan, Sabah
Email: achier300 at yahoo.com


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