الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Coral reefs are among the most diverse ecosystems on Earth. Coral reefs play important roles in ocean biogeochemical cycles. In particular, scleractinian corals are keystone species in tropical marine environments where they create the substrate and the three dimensional structures of the reef ecosystem, and also providing the majority of primary productivity within coral reefs. Red Sea corals are among the world’s greatest natural wonders.
Red Sea corals are cited among the most diverse in the world. A total 209 hard coral species and approximately 120 -125 soft coral species have been recorded in the Egyptian Red Sea. On average, coral diversity is greater in the northern part of Egyptian Red Sea than its southern part nearly double the number of coral species and genera.
The branching coral Stylophora pistillata and Acropora digitifera are of the most abundant hermatypic corals along the coasts of the Red Sea. Both of them could be found in shallow waters down to at least 60 m .they have been used for many years as a model species for coral biological studies.
S. pistillata and A. digitifera are a colonial coral characterized by the presence of numerous polyps, linked together by a common tissue, usually referred to coenosarc or coenenchyme, there are a strong morphological correspondence between the soft tissues and the calcareous skeleton from microscopic levels of observation. At microscopic levels, the skeleton of S.pistillata consists of Coralla which are branching; Calices in this species have rudimentary septa consisting of six primary septa fused with the columella and sometimes six short secondary septa, while the skeleton of