Etudes sur la dynamique des populations de l'oursin réguliers Paracentrotus lividus (Lamarck, 1816) au niveau de quelques stations de la côte de Mostaganem

Abstract

This study is part of an analysis of the dynamics of the populations of the common sea urchin Paracentrotus lividus (Lamarck, 1816) with the aim of studying its population dynamics at three stations on the coast of Mostaganem [Sidi-Mejdoub (SM), la Crique de Salamandre (CS), and Stidia (St)]. To do this, biometric measurements of the test length of the sea urchins were carried out on 312 sampled individuals of P. lividus (120 from St, 90 from CS, and 102 from SM) at regular intervals of 15 days over a period of 3 months (March, April, May 2023). The biometric data were collected and processed using the "FISAT II" program to analyze the population dynamics of this sea urchin using the Bathacharya method. The results showed the presence of five cohorts for the SM station, six cohorts for the CS station, and finally, seven cohorts for the St station. It should be noted that the further west the study station is located, the higher these size class modalities are compared to the stations located further east. This indicates an earlier recruitment in the stations that are further west compared to the east of the Mostaganem coast station. Surface ocean currents such as the modified waters of the Atlantic "Atlantic Water" (MAW) may play an important role in the expansion of P. lividus populations at the three studied stations. Therefore, recruitment seems to start first at Stidia, then at la Crique de Salamandre, and finally at Sidi Mejdoub.