Distribution of recent ostracods and benthic foraminifera from Farwa Lagoon (NW Libya)

Abstract

This paper presents the first detailed study of recent ostracods and foraminiferal assemblages found in the bottom sediments of the Farwa Lagoon on the northwestern coast of Libya. The studied assemblages consist of 25 ostracod species belonging to 17 genera, and 49 foraminiferal species, belonging to 21 genera. The abundance and diversity of these two groups of microorganisms vary among sites, providing the possibility of using ostracods and benthic foraminifera as bio-indicators in the Farwa Lagoon. Their distributions are influenced by many limnological conditions, including salinity, sediment types, the presence of seagrass cover, and hydrodynamic forces, as well as by pollution sources. Xestoleberis communis Müller, a common marine species, is the source of >40% of the ostracod valves counted and is found at 12 of the 15 sites. Six other species account for ∼30% of the valves, including Cyprideis torosa (Jones), Aurila convexa (Baird), A. woodwardii (Brady), Pontocythere turbida (Müller), Celtia emaciata (Brady), and Loxoconcha rhomboidea (Fischer). Foraminiferal tests are more abundant as well as more species rich, with tests of Ammonia parkinsoniana (d'Orbigny) making up 13% of the assemblage and only four other species accounting for at least 5%, notably Elphidium crispum (Linnaeus), Peneroplis planatus (Fichtel and Moll), Ammonia beccarii (Linnaeus), Quinqueloculina seminulum (Linnaeus). The foraminiferal species can be categorized as free-living (e.g., Quinqueloculina), and epiphytic taxa (e.g., Peneroplis, Ammonia, Elphidium). The identified assemblages are widely distributed in the shallow marine environments along the Mediterranean coasts, such as Morocco, Tunisia, Egypt, Turkey, Spain and Italy.