Bleaching in South Asia
reefmonitor at eureka.lk
reefmonitor at eureka.lk
Fri May 29 10:28:19 EDT 1998
Notice from the South Asia Regional Office of the
GLOBAL CORAL REEF MONITORING NETWORK
(GCRMN South Asia).
CORAL BLEACHING IN SOUTH ASIA
Below are a few preliminary reports of bleaching in the South Asia region
and some notes on near-future plans for assessing and documenting the same.
Bleaching in Maldives appears to have been relatively severe in the
short-term though there are reportedly already signs of partial recovery. At
a recent GCRMN South Asia methods training workshop at Bandos Island in
north Male Atoll a limited quantitative exercise was run on the local
house-reef on May 12th using LITs. Mean percentages of hard corals wholly or
partially bleached on our transects were around 80% on the back reef down to
around 45% at 10m on the reef slope. Personal observations indicated that at
20-30m on the reef slope at least 30-40% of hard coral colonies looked to be
at least partially affected. A rapid one day assessment in mid-May by Dr
Danny Elder on behalf of the Ministry for Planning, Human Resources and
Environment confirmed these figures are more or less representative of North
Male Atoll as a whole. No assessments by coral reef specialists are yet
known to have been conducted in other atolls, but reports to the Marine
Research Section in Male from atoll offices and local sea-plane operators
indicate that highs level of bleaching have occurred throughout the Maldives.
Recovery? William Allison spent the third week in May in South Male and
Vaavu Atolls, both south of North Male Atoll. He did not witness the
original extent of bleaching at these sites but suspects some recovery is
beginning to take place, possibly as a result of currents from the SW
monsoon causing upwelling of cooler water on the south and west sides of
atolls. Porites spp. appear to be recovering best (or least affected?). Many
acroporids appears to have suffered mortality however.
2. SRI LANKA
A similar picture is emerging on the SW coast of Sri Lanka. Prof. Suki
Ekaratne and co-workers of Colombo University have studied and reported over
70% bleaching at Hikkaduwa Marine Sanctuary, beginning from around the 10th
of April, 1998. Bleaching impacts on a number of coral spp. were recorded
photographically continuing from work ongoing over several months at
Hikkaduwa. A paper has been prepared.
Photographs taken by Arjan Rajasuriya of the National Aquatic Resources
Agency (NARA) on around 25th April at Hikkaduwa appear to confirm bleaching
in excess of 80% on the reef flat - there is no reef slope as such at
Hikkaduwa. Rajasuriya also observed bleaching earlier in the year in Jan/Feb
on deeper offshore reefs off Colombo, in particular Goniopora colonies and a
large tract of soft coral (Dendronephthya sp.). In general though he notes
that soft corals appear to have resisted bleaching better than Scleractinia
during the recent major event.
The Sri Lanka Sub-Aqua Club reported that all hard coral colonies on a
sparsely colonised reef at Wellawatte on the south coast were bleached.
An informal report from a tourist diver on the NE coast of Sri Lanka
(Trincolamalee) in early May on the other hand did not notice any bleaching
effects, though he was not specifically looking out for them. It could be he
isn't very observant. Local aquarium fish collectors on the SE coast
(Battilacoa) reported noticeable bleaching at lower depths (around 20m) in
mid-May, so it may be that the NE has also been impacted by now. These two
reports are only semi-reliable.
Dr Syed Ismail Koya of the Dept of Science, Technology and Environment in
Lakshadweep participated in the GCRMN training workshop in the Maldives in
early May and now reports that bleaching at Kavaratti Island, Lakshadweep
appears similar to what he witnessed in the Maldives, but perhaps somewhat
less severe. Sea conditions are too rough for quantitative survey work at
Rohan Arthur visited the Gulf of Kutch on the northerly Gujarat coast in
early-mid May. He has not yet analysed data from random quadrats but the
qualitative assessment is that bleaching varied between 10-30%. Bleaching
may yet worsen as warm water progresses north. Worth noting that corals in
Gulf of Kutch are not representative of other Indian or regional reefs;
their northerly location aside, corals there are severely stressed by
turbidity, sedimenation and probably hydrocarbon pollution.
4. FUTURE MONITORING PLANS
The SW monsoon will make it difficult to get into the water in many areas
but a number of in-water assessments are planned. To aid comparability, we
are encouraging researchers primarily to rely on LITs for local
quantification of bleaching.
In Maldives, the Marine Research Section, the Environment Research Unit,
William Allison and Danny Elder have all indicated they will try to get into
the field over the coming month or so and record quantitative or
semi-quantitative data. A group from UK associated with the Dunstanlab,
College of Charleston, South Carolina is also planning to visit Maldives in
In Sri Lanka, Dr Suki Ekaratne is continuing bleaching assessment work at
Hikkaduwa with regular photography-backed studies on tagged corals. A short
paper reporting reef bleaching has already been prepared. NARA is planning
to visit several sites on the SW coast during the coming 10 days or so, and
possibly the east coast within the next month, to conduct LIT surveys. Arjan
Rajasuriya (of NARA) will repeat photograph the Hikkaduwa reef to assess
recovery of tagged colonies. Ruhuna University's Dept of Fisheries Biology
plans to monitor bleaching of Polhena reef on the south coast.
In India, Rohan Arthur hopes to visit Lakshadweep in June but may be
thwarted by the weather. GCRMN is supporting a pilot monitoring exercise in
Lakshadweep with Goa University in September to collect detailed baseline
data at Agatti Island. The National Institute of Oceanography plan to begin
a monitoring programme at Chetlat Island later in the year. Dr K
Venkataraman at the Marine Biological Station, Zoological Survey of India
and Dr AK Kumararguru at Madurai-Kamaraj University plan to co-ordinate LIT
surveys in the Gulf of Mannar and Dr Soundararajan will continue ongoing LIT
surveys in the Andamans during June/July.
GCRMN aims to compile an integrated report on bleaching in the South Asia
region as soon as information becomes available - by end of July at the
earliest. The material will also be included in the regional review paper to
be presented at ITMEMS in Townsville in November this year.
PLEASE NOTE: IF ANYONE IS PLANNING TO VISIT THE REGION EITHER TO CONDUCT
RESEARCH OR AS A DIVING TOURIST I WOULD BE VERY GRATEFUL IF THEY COULD
CONTACT ME AT DETAILS BELOW, PREFERABLY BEFOREHAND, BUT CERTAINLY AFTERWARDS
IF THEY HAVE ANYTHING TO REPORT ON THE STATE OF ANY REEFS THEY MAY VISIT. WE
WILL INCLUDE ANY INFO. IN FUTURE REGIONAL REPORTS ON THIS LIST. THANK YOU.
Will also be glad to faciliatate contact between coral-listers and South
Asia regional researchers, some do not have e-mail access.
GCRMN South Asia
IOC-UNESCO/ UNEP/ IUCN
48 Vajira Road
Tel: + 94 74 511166
Fax: + 94 1 580202
GCRMN South Asia is supported by DFID, UK
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