reproductive cycle of the commercial sea urchin Paracentrotus lividus (Lamark, 1816) (Echinodermata: Echinoidea) in the Ionian Sea

The reproductive state of the commercial sea urchin Paracentrotus lividus was investigated during one year along a sector of the Ionian Sea of the Apulia region (Southern Italy). Gonadosomatic index, Repletion index and histological methods, categorized by four stages for females and two for male specimens were utilized to assess the reproductive cycle throughout an entire year with monthly sampling in four sites situated to north and south of Torre Suda (Gallipoli Municipality, Province of Lecce). The four populations exhibited similar reproductive pattern, having mature gonads and gonadal reconstitution during almost all months. The population from south of Torre Suda in August and March had the highest Gonadosomatic index values, the highest Gonadosomatic index values for the population north of Torre Suda was observed in February, March and April. Events of spawning were observed in spring, summer and autumn south of Torre Suda and in winter north of Torre Suda. In particular, spawning events were observed in medium-sized sea urchin (diameter 36–50 mm) with a high Repletion index value.