Optimisation du potentiel de reproduction chez Paracentrotus lividus vivant dans la baie de Mostaganem (Stidia)

Abstract

The main objective of this work is to assess the reproductive potential of the sea urchin Paracentrotus lividus (Lamarck, 1816) living in the coast of Mostaganem, more precisely in Stidia at two stations which have a mixed substrate rich in photophilic algae, the first is considered as a clean site and the second as a disturbed site impacted by human activities and urban waste. This study unroll from April to June 2021, where a total of 150 sea urchin individuals were sampled and processed. We first carried out the monthly monitoring of the measurements of the biometric indices (diameter D, height H and weight of the sea urchin), (Diameter Dla and Height Hla of Aristotle's lantern), and physiological indices (average gonadal index IGm and average repletion index IRm). Simultaneously with this monitoring a particle size study was initiated. The results of these analyzes showed by monitoring the indices that the spawning period takes place in the spring (April to June) and that the two sites are rich in nutrients. In a second step, we carried out in-vitro fertilization tests using sea urchins, sea water and sediment from the two sites (clean and polluted). Also to test the quality of the environment at these different sites, we used the larval development test of the sea urchin Paracentrotus lividus, a species widely used for this type of analysis. The main results of our study showed that, the sediment of two sites is composed of the fractions 0.1mm (fine sand) and 0.2mm (medium sand) with a dominance of the fraction 0,2mm, the OM rate of the own site is higher. to that of a polluted site. The rate of MRI and IGm shows a significant difference between the 3 months (April, May, June) according to the ANOVA test (p <0.05). On the other hand, no significant difference is marked between the sites. The fertility percentage represents different values which is 87% in the clean site, and 65.33% in the polluted site and 91.66% in the polluted site with sea urchins warning of the clean site. The larval development test indicates more or less healthy quality of the medium in the clean site, and poor quality compared to the level of the other site.