Abstract
Several samples of gastropod and pelecypod mollusk shells from three localities are selected along the Egyptian Red Sea coast. This is a study of the wall structure of some different shells of gastropods and pelecypod mollusks and their adaptive significance on evolution of the physical and chemical properties of the Red Sea water prevailing along the Egyptian shores and coasts. Analysis of gastropod and pelecypod mollusk shells of the study areas provides investigators with data to characterize the composition of these gastropod and pelecypod mollusk shells and to know the degree of human activities influence on the composition of the gastropod and pelecypod mollusk shells. Lambis truncata at Quseir and Safaga Harbors recorded the highest carbonate percentages (98.0 and 98.4%); meanwhile, Tridacna gigas at Quseir and Safaga Harbors recorded the highest organic matter contents (2.0 and 1.9%). On the other hand, Tridacna gigas recorded the highest values of organic matter in the study areas compared with the other species. The highest Ca contents were observed in Tridacna gigas and Strombus tricornis (71.1 and 69.6%) at El-Esh area, also the highest Mg was in Tridacna gigas (2.0%) at Qusier and Safaga Harbors, while the highest Sr was in Strombus tricornis at Qseir Harbor and El-Esh area (2473 and 2335 ppm). A study of the geochem-istry, X-ray diffraction contents of the common gastropod and pelecypod mollusk shells from Quseir Harebour, Safaga Harbor, and El-Esh area along the Egyptian Red Sea coast was carried out.