CORDIO Status Report 2000

es, metal bars and PVC surfaces. No recruits were
found on outer horizontal surfaces.
The taxonomic patterns of coral recruitment on the
SHED areas is shown in figure 2. Overall, the ratio of
branching to massive colonies was 67:33. This represents
a greater abundance of massive species than the initial
colonisation patterns recorded between 1990 and 1994,
where massive colonies represented less than 2% of the
entire population of corals. In total, nine genera of massive
corals were represented on the three SHED areas
from the following families: Poritidae, Faviidae and
Agariciidae. The dominant massive corals on the three
SHED areas were Porites lutea and Pavona varians.
There was considerable variation in the taxonomic
patterns of recruits on different settlement surfaces. The
highest percentage of recruits belonging to Acropora and
Pocillopora were recorded on outer vertical surfaces,
which concurred findings reported by Edwards et al.
(1994). Recruits with massive growth forms belonging
to Poritiidae and Faviidae were also found on both internal
and vertical surfaces. In contrast, the genus Pavona
was predominantly found on internal surfaces (91%).
Bioerosion and breakage
Although the dead stands of branching coral colonies
largely remain in-situ they have been subject to breakage
and erosion (Plate 3). Most of the dead coral surfaces
have been colonised subsequently by opportunistic species
including filamentous and macro-algae (Plate 4).
Repeated measurements of dead colonies on the SHED
and Armorflex areas have provided an early indication
of the extent of erosion of the reef framework. Many of
the large Acropora colonies with a tabular growth form
have shown a 40% - 60% decrease in mean colony diameter
in 6 months. However, it is not possible to determine
the causative agents (i.e. physical breakage, grazing
or bioerosion) and it is likely that a combination of
factors is involved. The magnitude and direction of
change in the reef framework and topographical complexity
of shallow reef flats may be crucial in determining
the time scales for reef recovery in Maldives.
Natural recovery processes
Coral recruitment patterns on the adjacent mined reef
were very patchy. The reef consists of raised coral boul-
Plate 3. Although many dead branching corals remained intact, their
skeletons were being degraded by biological and physical erosion and
breakage.
Plate 4. The exposed skeletons of dead corals are colonised rapidly
by filamentous algae and other opportunistic species.
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