Embryogenesis and Larval Development of the Omani Abalone (Haliotis mariaeWood, 1828)

Abstract

Recognizing the physiological changes of invertebrates during early life is essential to understand the species biology. Studies describing the development of early stages of Omani abalone (Haliotis mariae) are scarce. Therefore, this article presents the first detailed description of embryonic and larval development of the Omani abalone (H. mariae). The eggs obtained by a successful artificial spawning using a combination of hydrogen peroxide and ultraviolet irradiated- seawater, were observed carefully under compound microscope. The chronicle order of the embryonic and larval development of 26 distinct stages, from fertilization until reaching the presettlement stage when the larvae are competent and distinguished by formation of the third tubule tentacle, were illustrated. The changes during several stages were documented and photographed. The eggs were spherical, green, and negatively buoyant at the beginning then became planktonic; average fertilized egg diameter was 185 ± 7 µm. Hatching occurred at 9 h 16 min after fertilization, whereas larvae were competent at 46 h 48 min post fertilization. The average seawater temperature during the embryonic and larval observation was 24.7°C ± 1.0°C. The survival rate prior to settlement was 24.2%. This study provide a first detailed informative illustration of embryonic and larval development of Omani abalone (H. mariae), assisting in understanding the biology and ecology and supporting steps toward sustainable development of the aquaculture and management of this species.