Observations on the Breeding and Settlement ofMytilus Edulis(L.) in British Waters

Abstract

The literature on Mytilus edulis is particularly extensive. The most comprehensive account yet published is that of Field (1922), who gives excellent descriptions of the anatomy, physiology and embryology, as well as the bionomics, of this species. White (1939) adds little additional information upon the breeding and growth of Mytilus. Pelseneer (1935) gives an extensive bibliography covering both breeding and growth, whilst of the more recent work upon the breeding behaviour, the contributions of Battle (1932), Whedon (1936) and Young (1942) are most important. The occurrence oflarvae in the plankton has been described in detail by Thorson (1946) and others;Visscher (1927), Orton (1933), Kandler (1926) and many others have given much information upon the spat-fall and settlement in several localities.In spite of this wealth of published data there still remains considerable doubt over the time of onset and the duration of the breeding period of M. edulis, especially in relation to environmental factors. In particular, few recent investigations on Mytilus from beds in the sheltered and estuarine areas of the British coasts have been published, whilst the conclusions to be drawn from the older work (Herdman & Scott, 1895;Johnstone, 1898; Scott, 1900, etc.) are conflicting and lacking in precision. Finally, no attempt has previously been made to investigate the breeding, settlement and growth of this species simultaneously in a number of distinct geographical localities. This was the aim of the investigation, described below, which was commenced in 1946 as part of a general investigation of the breeding, settlement and growth of a number of common sessile littoral animals, and which is still in progress.

Annual variation in condition, respiration and remineralisation ofMytilus edulis L. in the Sound, Denmark

“…Spawning is usually triggered by increase in temperature (Bayne, 1975) and is reported to initiate at about 10~ [British waters: 9.5-12 ~ (Chipperfield, 1953); Baltic and Kattegat: approximately 10 ~ (Loo, 1991)]. In this study, temperature reached 10 ~ in mid May {Fig.…”

Comparative study of ecophysiological and biochemical variation between the Baltic and North Sea populations of the invasive soft shell clam Mya arenaria (L. 1758)

“…The sex and the development of gonads were determined by observations of the gonadal tissue under a microscope (400× magnification) and classified according to a 5-grade scale; 1-initiation of gametogenesis (immature), 2-development, 3-ripe gonad, 4-spawning, and 5-post-spawning (resting), adapted after Chipperfield (1953) and Sunila (1981). The gonad index (GI) was defined as:…”

“…The numerical values of the maturity stages were as follows: 1 − immature; 2 − developing; 3 − ripe; 4 − spawning; 0 − resting (Chipperfield 1953). The sex ratio in the populations was estimated based only on samples collected in spring and summer, when gonads were well developed, thus the determination of gender was possible for all specimens.…”

Biochemical‐genetic variation in a wild and a cultured population of the greenshell mussel,Perna canaliculus

“…Both M. edulis and P. canaliculus are broadcast spawning species which shed their gametes directly into the sea where fertilisation takes place. The larval duration of these species is estimated to be 2-A weeks (Chipperfield 1953;Jenkins 1985), which is sufficient time to allow for widespread dispersal of the larvae by currents and tides. This reason is often cited as one explanation why many populations of broadcast spawning marine invertebrates show very little if any genetic variation over very large geographic scales (100s and sometimes 1000s of km, e.g., Skibinski et al 1983).…”