Publications

Corals of Chagos, and the biogeographical role of Chagos in the Indian Ocean

A revised list of reef corals of Chagos contains about 220 zooxanthellate species of 58 genera, showing that Chagos is one of the most diverse sites for corals in the Indian Ocean. The hypothesis that Chagos? reefs are an important biogeographic link in the Indian Ocean is tested, firstly using GIS techniques. Similarities in coral species composition between Chagos and 25 other well sampled sites were computed, and a digital map of the Indian Ocean was resampled with GIS by replacing geographical with biological distances between sites. Biological distances were derived from species dissimilarity, and resampled maps were _anchored? on Chagos. Using second order then third order polynomial resampling methods, the map of the Indian Ocean is increasingly _warped?, pulling the extreme east and western sides (particularly the Red Sea) of the Ocean towards Chagos and towards each other, while the sites around the north-western and northern rim of the ocean are _pushed? further away. This is interpreted as support for the suggestion that Chagos is an important site or stepping stone in an east-west flow of coral species. A second technique which maps sites using multi-dimensional scaling was then used; this does not _anchor? Chagos but allows it to _float? freely with other sites. This confirms the closeness of Chagos to eastern and western Indian Ocean sites, and further suggests that the Chagos is linked to other central island groups of low latitudes

Authors

Sheppard Charles .

Year

1

ISBN-13

9781841030036

Keywords

Scleractnia (hard corals), biogeography, GIS, Geographic Information system, coral