Egyptian Journal of Biology, 2003, Vol. 5, pp 55-61 © Printed in Egypt. Modern Press. Egyptian British Biological Society (EBB Soc) Production of nursery-reared seedlings of the gray mangrove Avicennia marina under laboratory conditions Ali Gab-Alla 1 , Ishrak Khafagi 2* , Waleed Salama 3 and Moustafa Fouda 3 1. Marine Sciences Department, Faculty of Science, Suez Canal University, Ismailia, Egypt 2. Botany Department, Faculty of Science, Suez Canal University, Ismailia, Egypt 3. Nature Conservation Sector, Egyptian Environmental Affairs Agency, Egypt ABSTRACT Avicennia marina (Forssk.) Vierh. is the exclusive mangrove plant species that is naturally distributed along the Egyptian coast of Gulf of Aqaba, Red Sea. It has the broadest distribution, both latitudinally and longitudinally compared to any other mangrove species. In spite of the fact that mangrove forests usually grow in the intertidal zone, very few species such as Avicennia marina can grow in a truly saline environment. The aim of this study is to investigate germination of A. marina seeds and subsequent growth parameters of their seedlings in response to three different salinity levels composed of tap water, 50 % and 100 % seawater (0, 21, 42 ‰ salinity). Experimental results indicate that 21 ‰ salinity (50% seawater) has the highest germination percentage (%), leaf size (cm 2 ), internode length (cm) and plant height (cm). Moderate germination percentage, leaf morphology and stem growth was recorded for the tap- water treatment. The high salinity treatment of 42 ‰ (100 % seawater) inhibited seed germination. These results could be used in mass production of seedlings and saplings during the process of restoration of this threatened species. KEYWORDS: germination; leaf morphology; water salinity; Gulf of Aqaba; Red Sea, Sinai. INTRODUCTION Mangroves are usually found in tropical and sub-tropical marine inter-tidal zones (Tomlinson 1994) and are usually dominated by halophytic woody species (Suarez et al. 1998). Mangrove forests act as the borderline between land and sea. Their habitats are ecologically vital. They function as natural nutrient filters and recyclers, aid in floodwater improvement and protect coastlines from erosion, storm damage and wave action by acting as buffers trapping alluvial materials and thus stabilizing land elevation by sediment accretion that balances sediment loss (Balakrishna 1995). The ability to use seawater is one striking attribute of mangrove species. However, mangrove forests are threatened ecosystems (Duke 1990). Reclamation of mangrove land for agriculture, aquaculture, horticulture, human settlement, industries and salt production are some of the reasons for the present situation of reduction in mangrove forests all over the world. Coastal pollution with heavy metals and petroleum are also a threat to mangrove plants and their associated flora and fauna (Kairo et al. 2001), and they have also declined due to natural disasters (Jimenez 1985). Natural regeneration rates may continuously restore some of the destroyed mangrove areas, but it is rare for new mangrove patches to arise (Saenger & Siddique 1993). Avicennia marina (Forssk.) Vierh. (Avicenniaceae) is one of the most widespread mangroves in tropical and subtropical regions (Tomlinson 1994). It usually persists in a wide range of salinity levels and survives well in high salinity habitats, showing a distinctive shrubby form. A steady infusion of fresh water is essential to lessen the level of salinity in soil and water. Any reduction in the supply of fresh water results in an increase in salinity, which restricts mangrove growth (Jeminez 1990). _________________ * Address for Correspondence