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The fecundity and development of Moina macrocopa, the only cladoceran living in the waste water sedimentation ponds of Marrakech, have been studied in the laboratory at seven varying algal concentrations and at five different temperatures. Population density and grouping effects were also investigated.The conditions of food deficiency are one of the major cause of the reduced fecundity in Moina macrocopa. We showed, that an msufficientfood supply corresponding to an algae concentration lower than 3.125.10 4 cells/ml, would suppress (remove) any reproductive phenomenon. In contrast, the increase of resource level beyond this reproductive concentration threshold, allowed fecundity of Moina macrocopa to improve which appears as an increase in the brood number (frequency) rather than an increase of the brood size.The experiments also allowed us to show the harmful effect of an increase of population density on the fecundity of M. macrocopa. However, no grouping effect on reproductive processes has been observed in this species.

Parmi les caractères étudiés figurent : le taux de croissance, la taille à la maturité, la taille maximale, la durée de la phase juvénile, la durée de vie, la fécondité, le nombre de descendants par femelle, le nombre de portées et le nombre d'oeufs par portée.Les caractères démographiques des quatre populations révèlent leur adaptation à des conditions spécifiques et leur aptitude à se développer à des périodes différentes. Le faible nombre d'oeufs par portée, quelle que soit l'espèce, indique une limitation des ressources exploitables.The effect of temperature on the growth and reproduction of four species of planktonic Cladocera (Crustacea) reared with natural resources present Keywords : growth rate, reproduction, Crustacea, Cladocera, temperature.The growth and the reproduction of four species of Cladocera {Daphnia pulex, D. lumholtzi, Ceriodaphnia dubia et Diaphanosoma brachyurum) from a Moroccan reservoir (Lalla Takerkoust, near Marrakech) have been studied at five temperature (10, 15,20, 25 and 30°Q under natural environmental conditions (food and water quality). The characters studied are : the individual growth rate, the size of female at maturity, their maximal size, the duration of juvenile development, the duration of female life, their fecundity, the number of offsprings per female, the number of broods, the number of eggs per brood.The demographic characters of the four populations show their adaptation to various specific environmental conditions and their aptitude for developing in the reservoir at different times. The low number of eggs per brood in all species points out a limitation in the level of available resources.

Mots clés : régime alimentaire, Cladocères, phytoplancton, herbivore.L'examen du contenu du tube digestif des Cladocères de la retenue Lalla Takerkoust (Maroc) indique clairement la dominance phytoplanctonophage des espèces. Toutes les espèces sont des filtreuses herbivores, se nourrissant essentiellement d'algues. Cependant, chez les classes de petite taille il y a utilisation, en plus des algues, de détritus et de bactéries. La taille des animaux semble être un élément important dans la détermination de la taille des particules ingérées, ce qui confirme les résultats de Burns (1968). Les stades jeunes consomment principalement des micro-algues. A study of the diet of five species of Cladocera in the reservoir Lalla Takerkoust (Morocco)Keywords : diet, Cladocera, phytoplankton, herbivore.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.