Can macroalgae recover, 13 months after the 2004 Tsunami?: a case study at Talibong Island, Trang Province, Thailand

The tsunami that hit the coast of Thailand along the Andaman Sea on 26 December 2004 caused great damage to human life, property and coastal resources. Here we report the effect of the tsunami on the seaweed community, and its recovery, at Talibong Island, one of the affected areas in Trang province. We made surveys at three sites around the island from April 2004 to January 2006. Fifteen 0.5 m × 0.5 m permanent plots were set up on the west coast of the island to monitor changes in the seaweed community. Eighteen species were found. Sargassum stolonifolium and Laurencia composita were the most abundant, covering 90% and 39%, respectively, of the rocky substrate. Thirteen species varied among sites and seasons. Eleven species, however, were strongly affected by the tsunami. L. composita and Padina sanctae-crucis, for example, were initially washed up onto the shore by the strong wave action, which clearly resulted in a decrease in percentage cover. Also, many permanent plots were covered by sediment causing anoxic conditions, an indirect impact of the tsunami. A difference in species composition revealed a change in overall diversity. Particular morphologies and life forms were more sensitive to the extremes of the tsunami than others. Therefore, the recovery ability of populations of the affected species varied. We did not find any seasonal pattern to the recovery of seaweed after the tsunami within the 13 months of this study.