According to research reported this week in Current Biology, tsunami damage to coral reefs closest to the epicenter of the 2004 Sumatra-Andaman earthquake was occasionally spectacular, but surprisingly limited, particularly when compared to damage from chronic human misuse in the region.
Less than 100 days after the tsunami of December 26, 2004, a team of ecologists from James Cook University, the Wildlife Conservation Society-Indonesia Program, and Syiah Kuala University visited a number of reefs in northern Aceh. Some of the same reefs had also been visited in 2003, presenting a unique opportunity to assess the ecological impact of tsunamis on tropical marine ecosystems.
The researchers found that direct tsunami damage was largely restricted to corals growing in unconsolidated substrata, a feature that distinguishes tsunami damage from that of tropical storms, which typically have a greater affect on delicate corals in shallow waters.
The team also found that reef condition varied widely within the region and was clearly correlated with human activities prior to the tsunami. In areas where fishing has been controlled, such as the Marine Protected Area on Pulau Weh and reefs managed under the traditional Acehnese system of Panglima Laut, coral cover was high.
In contrast, reefs exposed to destructive fishing had low coral cover and high algal cover, a change that the tsunami may exacerbate in bringing an influx of nutrients and sediments.
However, the researchers found that there was no evidence to support the idea that healthy reefs reduced tsunami-induced damage on land. The authors concluded that although chronic human misuse has been much more destructive to reefs in northern Aceh than this rare natural disturbance, human modification of the reef environment did not contribute to the magnitude of damage on land.