CORAL REEF CONDITION IN RELATION TO CORAL REEF FISH ABUNDANCES BEFORE MASS BLEACHING EVENT IN SIMEULUE ISLANDS, ACEH

Bordered with the Indian Ocean, Simeulue Islands is one of the outermost islands in Indonesia located in the west part of Aceh Province. Simeulue waters are productive areas due to the unpolluted condition yet and great of biomass. Three regions were particularly observed, those are Simeuluecut, Ganting, and Labuhan Bajau. In those areas, the existing marine tourism activities might influence the coral reef ecosystem studied. This study aimed to evaluate the condition of coral and coral reef fish in those three particular regions before mass bleaching event in 2016 triggered by ENSO. Point Intercept Transect (PIT) method was employed to record the percentage cover of coral, species diversity, and coral reef fish. Ganting waters was a moderate ecosystem area whith the percentage coverage was up to 45.62%. However, in Simeuluecut and Labuhan Bajau waters, the coral reef communities were excellent with coral percentage coverage reached 83.12% and 81.25 %, respectively. The highest abundance genera of coral reef fish was observed in Simueluecut waters. This condition was changed oppositely in 2016 when mass bleaching threatened Simeulue waters due to temperature anomaly triggered by ENSO phenomenon. The temperature increases almost 3oC for 6 months that undoubtedly induced bleaching that about 50% of coral colonies were dramatically declined in coral coverage and coral recruitment.

Abnormal density of Culcita schmideliana delays recovery of a reef system in the Maldives following a catastrophic bleaching event

Culcita spp. are facultative corallivores that can have a selective effect on coral composition due to their feeding preference for Acropora spp. and Pocillopora spp. Although Culcita are normally rare (<0.5 per 100m2), mean densities of up to 9.2 sea stars per 100m2 were observed on a Maldivian reef system, with the highest numbers on the reef flat and reef crest. Culcita fed on 12 genera of corals, but showed a distinct preference for Pocillopora (51%) and Acropora (21%). Formerly the dominant corals on Maldivian reefs, these genera sustained 80–95% mortality from coral bleaching in 2016. Low numbers of juvenile acroporids and pocilloporids were slowly recolonising the reef, but 24% had recently been eaten by Culcita schmideliana. The abnormal abundance of C. schmideliana and high number of recently dead juvenile corals suggest that chronic predation by C. schmideliana could delay the recovery of reefs damaged by the 2016 mass bleaching event.

Conservation of Symbiodinium spp. clade in the coral Pocillopora damicornis during the 2014 mass-bleaching event

Symbiotic single-celled dinoflagellates play critical roles in providing corals with both energy and tolerances to survive over a range of environmental conditions. Stressors can cause the breakdown of this symbiosis, resulting in mass bleaching events, and are projected to increase in frequency and spatial extent, threatening the long-term survival of coral reefs. Recent studies have identified symbiont shuffling in corals towards more thermo-tolerant clades as a functional tool for their surviving thermally-induced stress events. However, this was not observed within Pocillopora damicornis colonies tracked over a complete bleaching to recovery cycle during the 2014 mass coral bleaching event in Hawai‘i. Instead, previously acquired symbiont clades were maintained following bleaching recovery. This observation suggests additional factors may be involved in thermal-stress acclimation and adaptation in this coral.

Conservation of Symbiodinium spp. clade in the coral Pocillopora damicornis during the 2014 mass-bleaching event

Symbiotic single-celled dinoflagellates play critical roles in providing corals with both energy and tolerances to survive over a range of environmental conditions. Stressors can cause the breakdown of this symbiosis, resulting in mass bleaching events, and are projected to increase in frequency and spatial extent, threatening the long-term survival of coral reefs. Recent studies have identified symbiont shuffling in corals towards more thermo-tolerant clades as a functional tool for their surviving thermally-induced stress events. However, this was not observed within Pocillopora damicornis colonies tracked over a complete bleaching to recovery cycle during the 2014 mass coral bleaching event in Hawai‘i. Instead, previously acquired symbiont clades were maintained following bleaching recovery. This observation suggests additional factors may be involved in thermal-stress acclimation and adaptation in this coral.