Edi Rudi

Acehnese Reefs in the Wake of the Asian Tsunami

The Sumatra-Andanaman tsunami was one of the greatest natural disasters in recorded human history. Here, we show that on the northwest coast of Aceh, Indonesia, where the tsunami was most ferocious, the damage to corals, although occasionally spectacular, was surprisingly limited. We detected no change in shallow coral assemblages between March 2003 and March 2005, with the exception of one site smothered by sediment. Direct tsunami damage was dependent on habitat and largely restricted to corals growing in unconsolidated substrata, a feature unique to tsunami disturbance. Reef condition, however, varied widely within the region and was clearly correlated with human impacts prior to the tsunami. Where fishing has been controlled, coral cover was high. In contrast, reefs exposed to destructive fishing had low coral cover and high algal cover, a phase shift the tsunami may exacerbate with an influx of sediments and nutrients. Healthy reefs did not mitigate the damage on land. Inundation distance was largely determined by wave height and coastal topography. We conclude that although chronic human misuse has been much more destructive to reefs in Aceh than this rare natural disturbance, human modification of the reef did not contribute to the magnitude of damage on land.

The role of habitat creation in coral reef conservation: a case study from Aceh, Indonesia

We describe the successful creation of new reef habitat on Pulau Weh, Indonesia. Coral cover on artificial reef modules increased from a mean of 24±SE 2.4% 1 year after the initial attachment of Acropora spp. coral fragments to 64±SE 4.8% after 3 years. The artificial reef modules were also rapidly colonized by coral recruits. Recruit densities were 53±SE 3.2 m⁻² on modules that had been submerged for only 1 year, nearly twice as high as recruit densities on natural reef substratum (31±2.8 m⁻²). Consequently, the original Acropora assemblage had increased to include at least 23 coral taxa, including 10 additional Acropora species. The artificial reefs also supported at least 29 reef fish species, from 11 families. Unfortunately, this initial success in habitat creation was abruptly halted by a rapid rise in sea temperature in May 2010 that killed almost all corals on the artificial reefs and on nearby natural reefs. Notwithstanding the general view that reef rehabilitation is yet to deliver ecological and conservation benefits at meaningful scales, other benefits of this project included raising the awareness of reef conservation in the local community, promotion of tourism on Pulau Weh and job creation. We conclude, therefore, that habitat creation has a legitimate role as part of an integrated marine conservation strategy.

The Coral Triangle Initiative: What are we missing? A case study from Aceh

The Coral Triangle Initiative (CTI) is an ambitious attempt to conserve the marine biodiversity hotspot known as the Coral Triangle (CT). However, the reef fauna in many nearby regions remains poorly explored and consequently, the CT focus risks overlooking other areas of high conservation significance. One region of potential significance, Aceh, Indonesia, has not been visited by coral taxonomists since the Dutch colonial period. Here, we document the species richness of scleractinian corals of Pulau Weh, Aceh, an important component of biodiversity. In addition, we also quantitatively compare the species richness of the Acropora at 3-5 sites in 9 regions in Indonesia and Papua New Guinea. While dominated by widespread Indo-Pacific species, the coral fauna of Pulau Weh is also the eastern and western boundary for many Indian Ocean and Pacific Ocean species, respectively. We identified a total of 133 scleractinian species; of these three were previously recorded only in the western Indian Ocean and five are presently undescribed. The mean species richness of the Acropora at Pulau Weh was similar to regions within the CT. This high species richness plus the high proportion of endemics suggests that the Andaman Sea is of similarly high conservation value to the CT. We suggest that an international initiative similar to the CTI is required to conserve this region that includes the territorial waters of six countries.