CORDIO Status Report 2000

and old limestone mixed among rocky habitats. The average
cover of live coral ranged between 10% and 15%
although small areas (< 100 m 2 ) supported coral cover
approaching 40%. The dominant corals were encrusting,
massive and laminar forms. Almost all corals were
bleached in 1998 but have since recovered.
Hikkaduwa Nature Reserve
This shallow coral reef once supported extensive areas
of branching Acropora spp. but was completely destroyed
by bleaching. Live coral cover was 7% in 1999
due to the recovery of several colonies of Porites, Goniastrea,
Favites and Favia. Colonies of Montipora aequituberculata
were not affected by the bleaching in 1998.
The abundance of butterfly fish has been reduced
considerably due to loss of live branching and tabulate
Acropora spp. The most common species Chaetodon trifasciatus
has declined from five individuals per transect
(Öhman et al., 1998) to less than three individuals in
post bleaching studies. At present, the Hikkaduwa Reef
lagoon is highly degraded by sedimentation and the loss
of live corals. Many corals are now buried under sand
and the exchange of water has also been restricted by
the accumulation of silt in one of the passages at the
southern end of the coral patch. Dead branching corals
were beginning to break up into coral rubble by late
1999. De Silva (1997b) reported that the abundance of
calcareous alga Halimeda sp. had increased to a level
where it was impeding the growth of live coral and was
also contributing to the increased sedimentation. This
species continues to be a problem within the reef lagoon.
A coral and rock habitat just outside the southern
boundary of the protected area supports coral in good
condition. However, this area is relatively deep (~10 m)
and therefore, the recovery of these corals is similar to
those on other reefs at similar depths. The dominant
coral genera were Favia, Favites, Plesiastrea, Goniastrea
and Echinophyllia.
Rumassala Reef
The condition of the Rummassala Reef was similar to
Hikkaduwa Reef but more colonies of coral survived
following the bleaching event because of their location
in deeper water (6 m – 8 m). Colonies of Porites rus,
which was the dominant species in shallow water, was
not bleached in 1998.
Sedimentation at Rummassala Reef was high and
the general appearance of corals was poor and comparable
to those corals in the Hikkaduwa Reef lagoon. However,
healthy corals belonging to the families of Mussidae
and Pectiniidae were found on the rocks close to the
watering point on the Rumassala headland.
Unawatuna
Coral bleaching in 1998 has destroyed almost all living
corals at Unawatuna. Surveys carried out in January
2000 determined that only colonies smaller than 1 m in
diameter are alive. Species of coral recorded were Porites
sp. Pocillopora eydouxi, Acropora sp. and Favites abdita
but generally the cover of live coral was negligible. This
strongly contrasts against investigations conducted in
1997 that reported cover of live coral of 47.1% (Table 3).
Fish abundance was extremely low. Only one specimen
of the butterfly fishes Chaetodon citrinellus, Chaetodon
decussatus and Chaetodon trifascialis was recorded.
Local tourism is a major threat to the reef at Unawatuna.
Trampling of the coral by reef-walkers, removal
of corals for souvenirs and increasing numbers of glass
bottom boats threaten the recovery process of this reef.
Weligama
All corals at Weligama were severely bleached except
Montipora aequituberculata and Psammacora contigua
which were only marginally affected and had recovered
completely by the end of 1998. In some parts of the reef,
colonies of Acropora formosa recovered after being
bleached for up to five months. All other corals including
Pocillopora verrucosa, P. eydouxi P. damicornis,
branching and tabulate Acropora spp. and the hydrocoral
Millepora were totally destroyed. Parts of the reef that
died after the bleaching are now covered in Halimeda
sp. and filamentous algae. Despite this, corals located in
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