Ecology of the metahaline pool of Di Zahav,Gulf of Elat,with notes on the siphonocladacea and the typology of near-shore marine pools

The hydrobiology of a metahaline near-shore pool, at Di Zahav on the Sinai coast of the Red Sea, has been studied. Salinity of the pool fluctuates between 45 and 60, and winter temperatures are as low as 10°C. The shore consists partly of beach rock, some of it still in statu nascendi. Serpulid reef-boulders also occur, covered with typical marine species. Three siphonocladacean green algae (Siphonocladus rigidus, Dictyosphaeria cavernosa, and Valonia utricularis), form abundant crusts on the boulders. Several peculiar faunal elements are discussed. Traits in common with the Suez Canal biota are discerned. A typology for the nearshore pools of Sinai is proposed.     

Life cycle ofRhopilema nomadica: a new immigrant scyphomedusan in the Mediterranean

Rhopilema nomadica is an Indopacific scyphomedusan, which has migrated into the eastern Mediterranean in recent years. Large aggregations of the medusae were recorded in Haifa Bay, Israel, reaching 5.5×10⁵ medusae per square nautical mile during summer 1989. The life cycle ofR. nomadica from planula to young medusa is described. Fertilization is external and planulae are formed within a few hours at 20°C. After settlement, polyps were fed withArtemia sp. nauplii and developed into polydisc strobilae within 45 d. The strobilation process was completed within 7 d, and the liberated ephyrae developed into young medusae within 2 mo. Asexual reproduction occurred mainly via podocyst formation. The population explosion ofR. nomadica could be attributed to its high reproductive potential.