Sustainable commercial or recreational harvesting activities, as well as aquaculture production of any species, require comprehensive information on the reproductive biology of the species. The common limpet (Patella vulgata) and the rough limpet (Patella ulyssiponensis) are protandrous hermaphrodite species, which are common on intertidal rocky shores of Portugal. This study describes the reproductive cycle of these two species from the Algarve coast (southern Portugal) and estimates their size at sex change. Between January 2017 and December 2018, individuals of P. vulgata and P. ulyssiponensis were collected monthly on a rocky shore at Praia da Luz in Lagos (37º05'06.5”N, 08º43'45.1”W) southern Portugal. In the laboratory, individuals were measured for shell total length (SL) and weighed for total wet weight (TW). To describe the main features of the reproductive cycle of both limpet species, classical histological technics were applied.
Both species had balanced sex ratios (P. vulgata = 1M: 0.98F; P. ulyssiponensis = 1M: 1.03F), similar size-frequency distribution between sexes, and equivalent mean shell lengths (SL) and total weights (TW) between males and females. In general, the reproductive cycles of P. vulgata and P. ulyssiponensis were characterised by a short resting period mainly during summer. In P. vulgata, ripe and spawning gonads were mostly recorded from early autumn until early spring, with a main spawning season in early spring to early summer. In P. ulyssiponensis, ripe and spawning gonads were scattered almost year-round, with a main spawning season also in early spring to early summer. The occurrence of ripe and spawning individuals throughout the year probably denotes sequential gonadal re-ripening and partial spawning events in both species. It was found correlative evidence of direct or indirect effects of surface seawater temperature (SST) on the reproductive cycle of both species, with the resting period coincident with warmer SST in summer, gametogenic development and gonadal maturation synchronised with decreasing SST during autumn, and main spawning season related to the increasing of SST throughout early spring to early summer. The extended spawning period of both species will allow obtaining larvae during most of the year, by arti?cial spawning induction of wild broodstock. In these protandrous hermaphrodites, the size at sex change (SL50) was estimated at approximately 29 mm for P. vulgata and 36 mm for P. ulyssiponensis (Fig. 1).
The present study was performed within the framework of the research project PESCAPANHA (funded by the Fisheries Operational Programme -MAR 2020- and co-financed by the European Maritime and Fisheries Fund - EMFF 2014–2020).