Fluctuations in settlement and survival of a barnacle Semibalanus balanoides in the White Sea intertidal

We tested whether the patchiness of barnacle settlement was determined by spatial (local) differences in settling and mortality rates. During the period of 2004–2011, annual photo-registration of a barnacles Semibalanus balanoides population was conducted on six flat rocks in the White Sea intertidal zone (Arctic). The average adult population density was 48 ind dm^?2, and the average barnacle age was 3–4 years. According to age structure, during the first year, the number of recruits dropped by three to fourfold; while in the following 2 years, the population density remained nearly the same. The effect of ice friction influence was not recorded, although the rocks were covered with ice in winter. Settling peaks were recorded in 2005, 2007, and 2009. No correlation was observed between the recruit and adult distribution during 2 years of intense settlement. The death rate was uneven on different quadrates along the transects but did not correlate with population density. Because high settling rates and mortality are not linked to specific sites, this suggests that population patchiness is not spatially stable.