The distribution patterns of Red Sea Chaetodontid assemblages

1. The occurrence and abundance of butterflyfishes were investigated in northern, central and southern areas of the Eritrean Red Sea coast. Visual census was used to estimate the presence and abundance of the species along 100-metre long transects. 2. The assemblages of buttertlyfishes from the three areas differ markedly. Two species are restricted to the north, while three others occur only in the south. The central area contains six species occurring in both the south and the north. 3. The results show that the chaetodontid assemblage of the northern area is more related to the central and northern region of the Red Sea while the southern area has many species in common with the Gulf of Aden. 4. The areas, sampled, are considered to represent different biogeographic regions within the Red Sea. It has been suggested that a barrier exists in the Red Sea, which prevents dispersal between the northern and southern regions. Our results indicate that this barrier is situated in the Eritrean central area. The nature of this barrier, however, remains unclear. Copyright (c) 2005 John Wiley & Sons, Ltd