A Comparison of the Annual Growth Patterns of Balanus balanoides (L.) with Particular Reference to the Effect of Food and Temperature

The annual growth in temperate waters of a number of cirripedes appears to be very similar: during the first year, rapid growth of the young spat follows the spring settlement and is succeeded by more moderate growth rates as the size increases during the summer; subsequently, in the autumn and winter little further growth takes place. This pattern is repeated annually as long as growth continues. Such a sequence appears to hold for Balanus balanoides (L.), B. balanus (L.) da Costa, B. crenatus Brug. and Verruca stroemia (0. Muller) (see BARNES, 1952-53, 1955 and 1958 a; BARNES and BARNES 1954; BARNES and POWELL 1953) at Millport, Scotland, and similar results have been obtained elsewhere (RUNNSTRbM 1925; HATTON and FISCHER-PIETTE 1932; MOORE 1934; HATTON 1938; BOUSFIELD 1954; CRISP 1954). When the effect of crowding, covering by mud or algae, and extent of intertidal exposure, are eliminated by semi-controlled raft exposures, the growth rate at any time of the year is seen to be particularly under the influence of the amount of food available. Food is particularly abundant during the planktonic phase and during the period when the young spat is growing vigorously. Indeed, it has been shown that in Balanus balanoides synchrony of nauplii release and the spring diatom outburst is achieved over the wide range of its distribution and the mechanism has been