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The so-called "band" diseases of reef corals, the White Band Disease (WBD) and the Black Band Disease (BBD), were observed in the Red Sea and in the Philippines. Since they were previously known only from the western Atlantic, this is the first record for the Indo-Pacific region.WBD is neither infectious nor contagious and the pathogen is unknown. BED is highly infectious and contagious and is caused by the cyanophyte Phormidium corallyficum. Susceptibility to WBD occurs throughout the order Scferactinia, but the effects of the disease are most severe among Acroporidae. Susceptibility to BBD seems to be restricted to Faviidae, with Plarygyra and Goniasfrea species the most heavily afflicted. WBD cannot be influenced by any parameter tested so far. BBD can be enhanced by light and by water eutrophication, and its advance can be stopped by antibiotics. An active WBD seems to be a precondition for the origin of BBD.

In April-May and in Scpte~iiber 1996, a total of 25 rcefs were studied between Taba and Ras Mohammed in the Gulf of Aqaba, Red Sea. In only four of these rcefs Drcpella corizus showed up in the transects in low nurnbers and coral diseases were found at a motlerate level on most reefs. Only the reefs of Ras ulnm Sidd, near Sharm el Sheikh, exhibited D l a p l l a C O~I Z L I .~ as well as c o d diseases both at abundant or even epidemic levels. There definitely s e e m 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 Dr~yelln cor?zi~s and thus promote a population cxpiosion, or does a massive D. comus invasion promote an epidcmic of White Syndromes on corals ?

The occurrence and distribution of the coral disease Skeleton Eroding Band (SEB) has been studied at the Jordanian coast in the Gulf of Aqaba, the northernmost extension of the Red Sea. The SEB syndrome is caused by the colonial, heterotrich ciliate Halofolliculina corallasia: an advancing front of these protists destroys polyps, coenosarc, and surface of the coenosteum. In recent years SEB was registered in reefs of Australia, Mauritius, and the Red Sea. Along the Jordanian coast, disease frequency at four study sites was investigated and afflicted coral genera and species were documented. The study sites were MSS (Marine Science Station)-north, MSS-south, the tourist area near the middle of the coast, and the industrial area adjacent to the Saudi Arabian border. Corals and infections were counted inside randomly placed 1 m 2 frames in reef flats and in 5, 10, and 15 m depths. In order of increasing affectedness of sample sites, MSS-south was the healthiest (12%, 4%, 4%, 16% of infected corals from shallow to deep), followed by MSS-north (19%, 28%, 24%, 24%), the tourist area (51%, 23%, 16%, 41%), and the industrial area (14%, 30%, 39%, 31%). By far the most frequently encountered coral species were Acropora spp. and Stylophora sp., while relative infection-rates were highest among Seriatopora sp. (75%), as well as Stylophora sp., Hydnophora sp., and Galaxea sp. (50% each). This was followed in steadily decreasing order from 44% to 5% by Pocillopora, Mycedium,

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