Species composition and distribution of medusae (Cnidaria: Medusozoa) along the Algerian coast between 2°E and 7°E (SW Mediterranean sea)

Abstract

The species composition, abundance and distribution of the medusa community along the Algerian coast (between 2°E and 7°E) were investigated during the autumn of 2014. Zooplankton sampling was performed in the upper layer (0-100 m) at 14 stations. Fourteen species of hydromedusae and scyphomedusae were identified. The hydromedusae populations were represented by Leptomedusae (5 species), Narcomedusae (3 species), Trachymedusae (3 species) and Anthomedusae (2 species). Some species, such as Cirrholovenia tetranema and Cunina globosa, were new species records for the sampling areas. The total abundance of medusae was less than 10 individuals. m-3. The areas with the highest concentrations (> 4 ind. m-3) were located along the central coast between the Bou Ismail (2.6° E) and Algiers (3.2° E) Bays. Here, the populations of Aglaura hemistoma and Liriope tetraphylla were dominant (≈ 40%). A quantitative variability was recorded for three species, Liriope tetraphylla, Pelagia noctiluca and Rhopalonema velatum, of which the first two species were particularly abundant in the central region and the latter species was particularly abundant in the eastern region. The distributions of these species were analysed in relation to the environmental parameters (temperature, salinity and chlorophyll a) and their interaction with copepod prey.