Population Structure And Growth Curve Of Acanthopleura Gemmata (Mollusca: Polyplacophora) In The Northwestern Red Sea

Abstract

Studies on Acanthopleura gemmata population were carried out in a site located on northwestern coast of the Red Sea called Sharm Elnagha, 40 km south of Hurghada city, Egypt (26° 56' N and 43° 00' E). In these studies, the population age structure, age and size at maturity, age and size at first reproduction, number of spawning times per year and per life span, rate of growth and type of growth curve were evaluated using the width of the 4th shell valve as a measuring character. The species population has 5-6 year classes, starts maturity at 1.5 years old when it is 13.5 mm 4th shell valve wide. Reproduction first occurred when the chiton was two years old and 17.15 mm 4th shell valve wide. The growth rate was higher in the O+ year class, steady in the middle classes and low in the oldest year class. The growth curve was a typical seasonally varying one and the growth rate was higher in winter and summer than in spring and autumn.