Disturbances affect
not only seagrasses, but also the abundance and diversity of associated macrofaunal communities. The
Andaman Sea coast of Thailand was heavily affected by the tsunami of December 26, 2004. To examine
its impact on seagrass macrofaunal communities, we compared the abundance, diversity and taxa
composition by quantitative samplings in 2001 (before the tsunami) and in 2005 and 2006 (after the
tsunami). Macrobenthic animals and sediments were collected from vegetated and nonvegetated areas of
two sites that had received different levels of tsunami disturbances. A large decline in abundance and
diversity was observed in the nonvegetated areas after the tsunami, whereas an increase was observed in
the vegetated areas. The magnitude of decline and subsequent recovery of abundance and diversity of
macrobenthic animals in nonvegetated areas were similar between the two sites, suggesting that their
temporal changes were not solely related to the magnitude of the tsunami disturbance. Similarity of the
benthic animals differed greatly between 2001 and 2005–2006 at the nonvegetated areas, whereas it
varied less among the 3 years at the seagrass-vegetated areas. This study demonstrated that the presence
of seagrass vegetation alters the patterns of temporal variation in macrofaunal assemblages and
subsequent recovery processes following a tsunami.