A possible link between coral diseases and a corallivorous snail (Drupella cornus) outbreak in the Red Sea

Abstract

In April-May and in September 1996, a total of 25 reefs were studied between Taba and Ras Mohammed in the Gulf of Aqaba, Red Sea. In only four of these reefs Drupella cornus showed up in the transects in low numbers and coral diseases were found at a moderate level on most reefs. Only the reefs of Ras umm Sidd, near Sharm el Sheikh, exhibited Drupella cornus as well as coral diseases both at abundant or even epidemic levels. There definitely seems to be a correlation between abundance of snail and diseases, but the question of "what comes first" remains to be investigated : does massive coral die-off (mostly White Syndromes) attract or benefit Drupella cornus and thus promote a population explosion, or does a massive D. cornus invasion promote an epidemic of White Syndromes on corals ?