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¹ University of Basrah, Marine Science Center, Basrah, Iraq
² University of Basrah, College of Agriculture, Basrah, Iraq Viewed : 4263 - Downloaded : 3086 Some biological aspects of the copepods, Apocyclops dengizicus and Mesocyclops isabellae were studied at a pool in Garmet-Ali during the period between August 1998 and July 1999. The laboratory sex ratio was in favour of the females: 3.6:1 and 2.06:1 in the two species respectively. The females of the two species showed faster growth during the copepodites IV, V and the adult. The males reached the adult stage at a shorter time than the females. All stages of life of A. dengizicus appeared in August 1998 and then disappeared. In February 1999, a few copepodites and adults were present, peaked in March and disappeared during April. M. isabellae appeared between August 1998 - December 1998, then disappeared and reappeared in April 1999. It is suggested that predation and cannibalism may be the causes of diapause in the two species. Keywords : cyclopoid copepods, mating, sex ratio, growth, population structure, Apocyclops dendizicus, Mesocyclops isabellae