FIRST STEPS TOWARDS THE PRODUCTION OF Patella vulgata AND Patella ulyssiponensis: REPRODUCTIVE CYCLE AND SIZE AT SEX CHANGE

The common limpet (Patella vulgata) and the rough limpet (Patella ulyssiponensis) are protandrous hermaphrodite species, which are common on intertidal rocky shores of Portugal. Sustainable commercial or recreational harvesting activities, as well as its aquaculture production, require comprehensive information on the reproductive biology of those species. This 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) and describes the reproductive cycle of P. vulgate and P. ulyssiponensis from the Algarve coast (southern Portugal) and estimates their size at sex change.

Twenty individuals of P. vulgata and P. ulyssiponensis were collected monthly between January 2017 and December 2018, on a rocky shore at Praia da Luz in Lagos (37º05ʹ06.5"N, 08º43ʹ45.1"W) located in the Algarve coast. 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.

For both species the sex-ratio was not significantly different from parityFigure 1. Size at sex change (SL50) in Patella vulgata and Patella ulyssiponensis (grouped into 5 mm SL classes). SL50 of each species highlighted with dashed lines.

. The reproductive cycles of both species were characterised by a main spawning season in early spring to early summer, sometimes including subsidiary spawning events. The present study 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. In these protandrous hermaphrodites, the estimated size at sex change was slightly smaller in P. vulgata (SL50 ≈ 29 mm) than in P. ulyssiponensis (SL50 ≈ 36 mm) (Fig. 1).