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International Journal of Marine Science 2013, Vol.3, No.38, 306-310
http://ijms.sophiapublisher.com
307
Figure 1 Map of the area including Hormuz Island where was examined in this study. SS= studied site in this study
the accumulated sediments collected with 10-day-sediment
traps following the methodology mentioned in Hill
and Wilkinson (2004). Three rods with 3 sedimentation
traps attached to each rod (9 traps in total) were
hammered to three sides of the reefs; however, the
data presented here are from 6 traps because the other
three traps were lost. Sedimentation rate is reported
as gr/cm²/day.
3 Results and Discussion
The main reefs of Hormuz Island, located at the east
and 2-4 m deep, include as main reef-builders
zoanthids and scleractinian corals for 59.79±15.95%
(mean±SD) and 8.68±7.01% (mean ±SD) of substratum,
respectively. The predominant coral genus in the area
is massive
Porites
(more than 85% of the
reef-building corals). High sedimentation rate is a
permanent characteristic of this site (Figure 2 A) and a
rate of 0.052±0.014 gr/cm²/day was measured. In spite
of this high sedimentation, corals and zoanthids have
appeared healthy during the last three years (Figure
2B, personal observations); however, in summer 2012,
the reef-building corals encountered coral bleaching
(Kavousi et al., unpublished data) and outbreak of a
disease that followed.
Overgrowth of invasive organisms such as algae
(Goreau et al., 1998; Barott et al., 2012) and pathogenic
Figure 2 A: Turbid waters due to high sedimentation around
coral reefs at eastern Hormuz Island B: Deposition of
sediments on live organisms such as corals and zoanthids as a
permanent characteristic of this site
bacteria (Kline and Vollmer, 2011) leading to coral
mortality is prevalent worldwide but mass coral
mortality from sulfate reducing bacteria is a rare
phenomenon that was recorded on reef-building
Porites
corals of Hormuz Island of the Persian Gulf in
Summer 2012.
Whereas all coral colonies were affected by thermal
stress (from partially bleached to fully-bleached), the
Porites
corals were overgrown by a white mat of
bacteria (Figure 3 A and B) that infected 96% of all
Porites
colonies and killed 58±30% (mean ± SD) of
all
Porites
tissues. The same phenomenon was also
observed on several coral genera on the south of
Hormuz and Larak Islands.