The Growth Of Balanus Balanoides (L.) and B. Crenatus Brug. Under Varying Conditions Of Submersion

Abstract

The length, breadth, and in part the height, of individual Balanus balanoides and B. crenatus have been measured over several seasons, and the mean specific growth-rates calculated. The B. balanoides had settled at various known intertidal levels, and both species under conditions of permanent submersion.Under all conditions, except on the highest intertidal panels, length increases rapidly subsequent to settlement and during the early summer. B. crenatus can reach its virtual maximum size (20–25 nun. rostro-carinal length) in a single growing season, under the conditions studied. Late-settled B. crenatus continue to grow further into the autumn, and begin to grow again early in the spring of the second season at the end of which the virtual maximum size is reached. The seasonal growth of both intertidal and submerged B. balanoides is similar, but the growth-rate is a function of submersion, which is, of course, dependent upon the tidal level. However, maximum growth is not reached in the first season and there is consequently relatively more growth in the second season than in B. crenatus.The mean specific growth-rates in both species decrease with increasing size and, with permanently submerged B. crenatus, there is no suggestion that during the first spring and early summer any change in the environmental factors was effective. On the intertidal panels, the mean specific growth-rates at a given size vary with the tidal level, and this effect is most marked in the smaller barnacles.