Variabilité interspécifique de trois algues rouges : Hypnea musciformis, Gracilaria multipartita et Gelidium sesquipedalen(Rhodophycées) de la côte atlantique marocaine

Interspecific variability of the red algae: Hypnea musciformis, Gracilaria multipartita and Gelidium sesquipedale (Rhodophyceae) of the Moroccan atlantic coast Total analysis of the growth of three red algae species; Hypnea  musciformis , Gracilaria multipartita and Gelidium sesquipedale were undertaken with an aim of determining interspecific variability within the same natural environment. The studied site is the beach of Mehdia located at the north of the Moroccan Atlantic coast. The results show specific differences in the growth rates of the three studied species. Gracilaria multipartita presents a significant development of the growth parameters like the size, the weight and the total ramification, especially for the aestival period compared to Gelidium sesquipedale and Hypnea musciformis . The active growth periods of Gracilaria multipartita are characterized by slightly important temperatures and light intensities and by high percentages of nitrates and phosphates. On the other hand, the growth of Hypnea musciformis shows fluctuations due to the variations of the environmental factors. The growth of Gelidium sesquipedale is slow and seems more under the influence of intrinsic factors than environmental factors.