The biota of reef-flats and limestone cliffs near Jeddah, Saudi Arabia

Abstract

Summary (1) The Jeddah reef-flat is subject to marked seasonal changes. Mortalities of reef fish and invertebrates may occur during winter. High summer temperatures and salinity, coinciding with low seas, cause migrations of certain gastropods towards the breaker zone. Sargassum sp. grows densely in the breaker zone from the late spring to late November. Thereafter heavy seas tear up the fronds which contribute to the inshore detritus. Many invertebrates commence breeding in early spring. (2) A comparison of the faunas of limestone cliffs from Jeddah, Port Sudan, the extreme north and south of the Red Sea, and Aldabra Atoll suggests that the Jeddah fauna is impoverished by the limitation of suitable intertidal surfaces imposed by the lack of tides and by the moderate exposure to wave action.