Studies on the biology of limpets IV. The breeding of patella depress a pennant on the north Cornish coast

Abstract

SUMMARYThe breeding of Patella depressa was studied at Trevone, North Cornwall, for 4 years. Gonads were examined and assessed by methods described in a previous report on P. vulgata.In contrast to the common Limpet, P. depressa is a summer breeder in Cornwall. Gonad development begins in the spring and is complete by June or July. Spawning coincides with maximum air temperatures in July, August or early September. The autumn and winter period is passed with gonads in recognizable post-spawning and spent stages, and only a small proportion of completely resting neuter gonads is found in the early spring.Mass spawning takes place, and gametes are voided rapidly. No definite spawning stimulus can be shown, but, as with P. vulgata, there may be some relation between onset of spawning and the occurrence of wave action on the shore.The differences in breeding behaviour of P. depressa and P. vulgata reinforce the other differences between them and throw some doubt on the concept of super-species in Patella.

The reproductive cycle ofPatella candei gomesiiDrouët, 1858 (Mollusca: Patellogastropoda), an Azorean endemic subspecies

“…This is in contrast to what has been described for Patella depressa from exposed and sheltered sites in the centre of Portugal (Cabo Raso, Cascais). Morais et al (2003) found that, in the summer, gametogenesis in limpets from the exposed site was more advanced (mainly stage III and stage IV) than that in limpets from the sheltered site (stage III), according to the maturation scale of Orton et al (1961). The similar reproductive cycles of the two ecomorphs described in this study may reflect phylogenetic preservation of reproductive patterns, as referred to by Henninger and Hodgson (2001).…”

“…Summer spawning events have been reported for Patella vulgata in NE England (August: Bowman and Lewis, 1986) and in Portugal (September/October: Guerra and Gaudêncio, 1986). P. depressa has also been identified as a summer breeder in Britain (Orton and Southward, 1961) and in Portugal (early summer and early autumn: Guerra and Gaudêncio, 1986). The fact that in P. candei gomesii the levels of gametes remain high until January is not surprising, as P. depressa in the south of Portugal also presents fat and ripe gonads over the winter season (Guerra and Gaudêncio, 1986).…”

“…Species with planktotrophic larvae spawn just prior to the time when plankton is maximal (ensuring food for the larvae) at a time of rising or high sea surface temperatures (Branch, 1981). In fact, spawning in P. depressa seems to coincide with maximum air temperatures (Orton and Southward, 1961;Fretter and Graham, 1976). Such is the case for P. candei gomesii.…”

“…Several studies have been undertaken concerning the reproductive cycles of Patella species (Orton et al, 1956;Orton and Southward, 1961;Blackmore, 1969;Lewis and Bowman, 1975;Bowman and Lewis, 1986). Most are based on the macroscopic index described by Orton et al (1956).…”

Reproduction of Patella spp. on the Basque coast of Spain

“…aspera) of Guerra & Gaudencio (see this volume). They contrast strongly with data from Britain and Ireland (Orton & Southward, 1961;Thompson, 1979;Bowman, 1985;Bowman & Lewis, this volume) where gonad activity is of much shorter duration and usually confined to midsummer and/or early autumn.…”