Physiological Indices and Feeding Behavior in the Paracentrotus lividus Populations from the South Coast of Morocco

The main objective of this study was to describe the variations of the physiological indices and the feeding behavior in the populations of Paracentrotus lividus from the southern coast of Morocco. The annual change in the gonad index (GI) and the repletion index (RI) were the first parameters investigated. The effect of the environmental parameters (pH, temperature, salinity, and photoperiod) on the monthly evolution of the gonad index was also studied. Furthermore, the feeding behavior of the sea urchins was analysed. From March 2018 to February 2020, three sites (Cap Ghir, Sidi R'bat and Anza) were sampled monthly and physico-chemical analyses (temperature, pH and salinity) of the water were carried out in situ. The findings obtained show that the physico-chemical parameters of the waters at the various examined sites are favorable for the growth of the sea urchin P. lividus . Between December and February, a consistent annual gametogenic cycle was observed with a high GI increase, associated with a rise in temperature and short day duration, followed by a single spawning period between March and August. In autumn and winter, regardless the biotope, the studied species has a high RI increase. The relation between these two indices has been highlighted; the high consumption period is related to the maximum maturation period of the gonads. The gut content analysis reveals that P. lividus mainly consumes the following algae species; Bifurcaria tuberculata, Dictyota dichotoma, Padina pavonia, Cystoseira humilis (spp ), Ulva lactuca, Corallina officinalis, Asparagopsis armata.