Publications

Effects of the tsunami in the Chagos Archipelago

The five atolls and numerous submerged atolls and banks of the Chagos Archipelago are all separated from each other by very deep water, and there are no broad or gently shallowing shelves between the atolls and the site of origin of the December 2004 tsunami. Effects of the recent tsunami in Chagos were mixed. The vegetation of some islands has been damaged in places, but nowhere very extensively. Following an inspection of many islands in all 5 atolls in February 2005, it was clear that the results of the tsunami must be looked at in the context of the shoreline erosion that is taking place in these islands. It appears likely that the tsunami accelerated coastal erosion by 1-2 years on eastern sides at least. Almost all damage seen on land was on eastern sides, where undergrowth vegetation was stripped away in several places, leaving only mature palms.In the sublittoral, most of these eastern areas had low cover by stony and soft corals, but this was also the case in 1999 and 2001 when coral and soft coral cover was drastically reduced, whose cause was attributed to the 1998 mass mortality. Most areas which now have low benthic cover used to be dominated by soft rather than hard corals; soft corals have shown poor recovery to date in any location in this archipelago. Most western facing seaward reefs previously dominated by stony corals show stronger coral recovery from 1998 than do most eastern facing seaward locations. However, some western facing seaward slopes on Diego Garcia still show very low cover, as was the case in 1999 and 2001. There is no consistent pattern to suggest that the tsunami had any widespread sublittoral impacts, and present coral and soft coral cover appears to be much more strongly determined by the legacy of 1998 and differential recruitment of benthic groups. Substantial movement of sand was observed on eastern and southern Salomon atoll, and shoreline erosion was marked in many places in all atolls. Refraction around atolls was minimal such that, with one exception, no damage was seen on western sides of atolls.

Authors

Sheppard Charles .

Year

1

DOI

10.5479/si.00775630.544.1

ISBN-13

0

Keywords

Scleractnia (hard corals),Octocorallia (soft corals),terrestrial flora(other), tsunami

Link

http://www.sil.si.edu/digitalcollections/atollresearchbulletin/ARB_search.cfm