Recruitment, growth and population size structure of Pollicipes pollicipes in SW Portugal

Size structure analyses of P. pollicipes attached directly to primary substratum and/or to the base of conspecifics showed that barnacles at the low tide level reached a higher maximum size, indicating that growth at this level was faster than on the high shore. A higher temporal variability between these size-frequency distributions was detected in spring (March to May). In March, two cohorts (< 1 year old, > 1 year old) were identified. In May and August, it was difficult to identify individual different cohorts. From mid autumn to early spring, as a consequence of recruitment of barnacles to the primary substratum, it was again possible to identify two cohorts.