ASPECTS OF THE POPULATION-DYNAMICS OF CHTHAMALUS-DENTATUS (CRUSTACEA,CIRRIPEDIA) ON THE TRANSKEI COAST OF SOUTHERN-AFRICA

Long-term fluctuations (3-9 years) in the abundance of the barnacle Ch thamalus dentatus were determined from archival photographs of permane nt 0,25 m2 quadrats in the mid-littoral at 11 sites along the Transkei coast. These data were combined with a more detailed analysis of grow th and recruitment over one year. Recruitment occurred in spring and a utumn, but periodogram analyses revealed additional cycles with freque ncies of 24-36 months. There was no geographic pattern in long-term di fferences in abundance between sites nor were these related to human d isturbance. Recruitment intensity was significantly related to mean ab undance of adults, which may indicate limited larval dispersal or greg arious settlement. Maximum aperture length increased by 3,0 mm in the first year but increased by only 1 mm . year-1 in the third year. Indi vidual growth was variable, with small individuals often overtaking la rger ones. There were few large individuals, those of 7,0 mm or more c onstituting only 3% of the population. An analysis of longevity indica ted a mean lifespan of 1,5 + 0,5 years.