Reproductive cycle of the sea cucumber Holothuria tubulosa (Holothuroidea: Echinodermata) in the Southwestern Mediterranean Sea

Abstract

Aspidochirotid holothurians, commonly known as "sea cucumbers", are conspicuous component of Posidonia oceanica meadows of the Mediterranean Sea, where they are reported as generally large sized and rather abundant. They actively contribute to the functioning of the Posidonia meadow by recycling dead organic matter in the sediments layer, which confers them a major ecological role. This study is a first contribution on the reproductive biology of Holothuria tubulosa (Gmelin, 1790) collected from the South-Western Mediterranean, especially from the Algiers coastal area. The sampling was conducted in Ain Taggourait station (w. Tipasa) which is an unpolluted area under little anthropogenic influence. The temporal evolution of the gonad index (GI) and the sexual maturity stages suggest that the reproductive cycle of H. tubulosa is annual and marked by a main spawning taking place from June to august. We also show the synchronization of the maturation of gonads in both sexes of this species. The influence of temperature is the most likely factor influencing its reproductive cycle and the spawning of H. tubulosa. The general outline of the gametogenesis of H. tubulosa shows a winter sexual resting phase, followed by maturation in spring and spawning at the end of summer until a middle of autumn.