Reproductive cycle of Spisula solida (L.) (Mollusca: Bivalvia) on the southwest coast of Spain

The reproductive cycle of Spisula solida (L., 1758) was investigated for the first time in the southwest of Spain, using specimens collected from Punta Umbri{dotless acute}a (Huelva), between April 2001 and May 2002. A total of 2805 individuals of shell lengths ranging from 9.1 to 38.4 mm were analysed. The gonad development was determined by means of histological methods and variations of dry weight. Five gametogenic stages were identified (I-Immature, II-Maturing, III-Ripe, IV-Spawning, V-Post-spawning). The sex-ratio obtained was 5:4 (χ2 = 6.12, df = 1, p > 0.01), males being more abundant than females. Two hermaphrodite individuals were recorded. Development of the gonad began in November and spawning occurred between December and June, with maximum peaks in April (82% males) and May (87% females). The period of sexual rest took place from July to October. Gametogenesis in this species is a response to low seawater temperatures, and spawning occurs with low temperatures that increase progressively. Copyright © 2013 Taylor & Francis.This research was supported by the IFOP project.Peer Reviewe