Settling intensity (i.e. sum of individuals settled during subsequent one month periods on clean Plexiglas panels) and settling success (i.e. numbers of individuals at the end of the colonization period found on fouling panels submerged since the beginning of the experiments in March/April) have been monitored at the island of Helgoland (North Sea) from 1977 to 1986. The settling intensity and settling success of Elminius modestus showed characteristic deviations in some years during the 10 years studied. Very weak settling intensity and success were registered in the summer of 1979, 1980, 1982 and 1986. With the exception of 1980, these low settling intensity and success may be explained by unusually cold winters which in these years preceded the season of colonization and visibly decimated adult populations in the German Bight (significant positive correlation between water and air temperatures during winter months and subsequent colonization intensities of E. modestus). It is assumed that this barnacle species, which was introduced from New Zealand only 45 years ago, is subject to considerable genetic selection pressure towards cold adaptation.