GCRMN_COI_2017-Western Indian Ocean Reef Status

Coral reef status report for the Western Indian Ocean (2017)
Global Coral Reef Monitoring Network
The initial phase of recovery was dominated by coral genera other than Acropora, in 2005
making up 12% of reef cover compared to 1% for Acropora. As time passed Acropora
recovery has accelerated, reaching 22% in 2015, when for the first time it surpassed
mean non-Acropora coral cover. Between 2005 and 2012, sites located in protected areas
had similar levels of live coral cover as those found at unprotected locations. However, by
2013 coral cover within protected areas exceeded that in unprotected areas by a margin
of about 10% (fig. 2.7.3a). On average the abundance of macro-algae has remained
relatively low (1.2%) at monitoring sites between 2005 and 2015 (fig. 2.7.3b). However,
other sites in the inner islands are reported to have undergone a phase-shift from coral to
macro-algae domination (see Graham et al., 2015).
Figure 2.7.3: a) hard coral cover on protected and unprotected reefs, and b) fleshy algae and
hard coral cover trends in the Seychelles inner islands.
NATIONAL CHAPTERS
Mean hard coral cover on the reefs of Aldabra in 2015 was around 30% on the shallow
reefs and around 18% on the deeper reefs. A gradual increase in hard coral cover has
been recorded over time for the shallow reefs whereas deeper reefs have remained fairly
consistent. This is consistent with data collected as part of the reef mapping project
undertaken in 2012 which recorded higher mean coral cover on shallower transects than
deeper ones. However there was high level of heterogeneity in coral cover on the reefs of
Aldabra with sites ranging between 2 to 44% (Chong-Seng, 2015). Data collected during
the mapping survey indicates that there are sites where hard coral cover in excess of 80%
exists (Haupt et al., 2015).
In the other outer islands coral reef monitoring has been done opportunistically and
available data and trends are summarised in Table 2.7.1.
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