Reproduction parthenogenetique de Moina macrocopa (Straus 1820) (Crustacea: Cladocera). Influence des conditions trophiques, de la densite de population, du groupement et de la temperature

Abstract

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 insufficient food supply corresponding to an algae concentration lower than 3. 125.104 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.