Etude de la biologie de reproduction d’Arbacia lixula (Linnaeus, 1758) de la côte de Mostaganem

Abstract

A study of the reproduction of the black sea urchin Arbacia lixula from Mostaganem coastline was conducted at two different sites, one (Salamander) rocky, rich in photophilous algae but disturbed by pollution (urban and industrial discharges) and high port activity ; the other (Stidia) with mixed substrate, relatively healthy and rich in photophilous algae. This work, spread over 10 months (December 2013-September 2014) and performed on 588 individuals, consisted to follow the monthly evolution of physiological indices (gonad index and index of repletion), the sex ratio and histology of the males and females gonads. The effects of temperature and seasons and allometric relationships between several morphological parameters were also evaluated. The sex ratio, regardless of the biotope is slightly in favor of males with a slight monthly alternating between the sexes. According to the gonad index and gonad histology, the spawning period is located in the spring-summer, from May to September and is possibly trigger by spring temperatures (20-23 ° C). Allometric relationships between different morphological parameters, diameter and height of the test without spines, height and diameter of Aristotle's lantern, diameter of the test without spines and diameter of Aristotle's lantern, test diameter without spines and wet weight, test height without spines and wet weight, demonstrate the existence of a more than average allometric relationship between these different growth parameters and reflect the flattening of the black sea urchin A. lixula that can be regarded as a form of adaptation to its middle. Histological results of the male and female gonads of these sea urchins in these two contrasting sites (salamander and Stidia) correlate perfectly with gonadal indices and validate the consideration of this parameter (gonad index) in the evaluation of gonadal growth and determination of their maturation stages.