Etude du régime alimentaire de cinq espèces de Cladocères dans la retenue Lalla Takerkoust (Maroc)

Abstract

The examination of the gut contents of cladocerans from the reservoir Lalla Takerkoust (Morocco) showed clearly the dominance of phytoplankton feeding by these species. All species are herbivorous filter-feeders that feed on algae. However, in the smallest size classes, detritus and bacteria are utilized as well as algae. The specific nature of the diet is more or less marked amongst the species, especially daphniids. Diaphanosoma brachyurum (Lievin 1848) and Ceriodaphnia dubia (Richard 1894) appear to be passive filterers. Certain species, such as C. dubia, D. brachyurum and Bosmina longirostris (O.F. Müller 1785) have an alimentary fan that is identical and more closed than that of other species. They feed on Cyclotella ocellata (Pantocksek), Schroederia sp. and Euglena sp. In addition, Daphnia lumholtzi (Sars 1886) and Daphnia pulex (Leydig 1860), both species of large size, have a larger range of diet. As well as Cyclotella, Schroederia and Euglena sp., D. lumholtzi feeds on Cosmarium laeve (Rabenhorst) whereas D. pulex feeds on Cyaophyceae and Dinophycae. Animal size seems to be an important element in determining the size of ingested particles, which confirms the results of Burns (1968). The young stages consume chiefly micro-algae. © Gauthier-Villars, 1994.