Reproductive cycle of the common limpet (patella vulgata) and rough limpet (patella ulyssiponensis) in southern Portugal

Umapathy, Uthesh

http://hdl.handle.net/10400.1/19812

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Authors

Umapathy, Uthesh

Advisor(s)

Gaspar, Miguel B.

Moura, Paula

Abstract(s)

The common limpet (Patella vulgata Linnaeus, 1758) and the rough limpet (Patella ulyssiponensis Gmelin, 1791) are common species in intertidal rocky shores along the Atlantic coasts of Europe. Both species are collected by professional harvesters and recreational harvesters in mainland Portugal. These patellid limpets are protandrous hermaphrodites that have been subject to diverse studies on reproductive features throughout their distributional ranges along the coasts of the northeastern Atlantic Ocean. In order to describe the reproductive cycle of P. vulgata and P. ulyssiponensis, individuals of both species were sampled monthly from intertidal rocky areas from Praia da Luz in Lagos (Algarve coast – southern Portugal) during two consecutive years (January 2017 – December 2018) and subjected to gonad histology and calculation of the mean gonadal index (GI). Overall, were analysed 882 individuals with broad size ranges, 444 P. vulgata (19.5 – 43.0 mm SL) and 438 P. ulyssiponensis (12.3 – 55.4 mm SL). Both species presented balanced sex ratios (P. vulgata = 1M: 0.98F; P. ulyssiponensis = 1M: 1.03F), similar size-frequency distribution between sexes and equivalent mean shell length and total weight between males and females. The estimated size at sex change was slightly smaller in P. vulgata (SL50 ≈ 29 mm) than in P. ulyssiponensis (SL50 ≈ 36 mm). 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 – early summer. In P. ulyssiponensis, ripe and spawning gonads were scattered almost year-round, with a main spawning season also in early spring – early summer. Both species also displayed subsidiary spawning events scattered throughout the year (variable depending on the sampling year). The reproductive cycles of P. vulgata and P. ulyssiponensis were influenced by the seasonal variation in surface seawater temperature (SST), with resting periods coincident with warmer SST in summer, gametogenic development and gonadal maturation triggered by decreasing SST during autumn, and main spawning seasons roughly synchronised with increasing SST during early spring – early summer. Populations of P. vulgata and P. ulyssiponensis from southern Portugal have the later spawning period reported throughout their distributional ranges in the northeastern Atlantic Ocean. Overall, this study provides relevant information for conservation purposes and for the proposal of management measures for the harvesting of P. vulgata and P. ulyssiponensis in southern Portugal.