Gametogenesis and Reproduction Cycle of the Burrowing Urchin Echinometra mathaei (Echinodermata: Echinoidea) from the Northern Red Sea

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The burrowing sea urchin Echinometra mathaei (Blainville, 1825) is a common species found on reefs in the tropical regions of the Indo-Pacific Ocean, typically at depths of up to 139 meters. The gametogenesis and reproductive strategy of the E. mathaei population were investigated at two study sites: Al-Ain Al-Sukhna public beach and Hurghada in the northern Red Sea, from spring 2023 to winter 2024. To examine sexual differences in gonadal maturation, histological sections of E. mathaei gonads were analyzed. At the first site, reproductive activity peaked in late summer and continued into autumn, while at the second site, fully mature oocytes were observed year-round. Following laboratory induction of spawning, the fertilization rate increased to 90%, reaching the prism stage. Environmental factors, such as temperature and salinity, were found to affect reproductive state and gonadal development. Sea water temperatures rose in summer 2023, coinciding with an increase in gamete size at both study sites. The diameters of oocytes and spermatocytes reached their maximum values in autumn (532.01 and 170.38µm at the first site; 535.4 and 170.21µm at the second site). These results indicate that temperature is a significant factor influencing the gametogenesis processes.

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